If you’re reading this, your store probably just did the thing: a routine update, a refresh, and suddenly WordPress serves the dreaded “There has been a critical error on this website.” Orders stall. Checkout dies. Your marketing team starts “just checking in.”
Good news: most WooCommerce post-update failures are recoverable without data loss, and the fastest path back isn’t heroic debugging—it’s disciplined rollback, tight log-reading, and protecting the database like it pays your salary. Because it does.
Table of contents
What “critical error” actually means in WooCommerce land
That message is WordPress’s polite wrapper around a PHP fatal error. It’s not a diagnosis; it’s a seatbelt. WordPress catches the fatal, avoids splashing a stack trace on your storefront, and shows the “critical error” page. Behind it is usually one of these:
- A plugin update introduced an incompatibility (PHP version, WordPress version, other plugin, theme hooks).
- A theme update (or custom theme code) is calling removed WooCommerce functions.
- A partial update left files mismatched: half new code, half old code.
- Opcode cache (OPcache) is serving stale code while the filesystem has moved on.
- A database migration ran and then failed mid-flight, leaving schema or options inconsistent.
- A server-side change coincided with the update: PHP module changes, file permissions, disk full, or a corrupted autoloader.
When WooCommerce is involved, there’s one extra angle: WooCommerce updates sometimes include database migrations. Those are usually safe and idempotent, but “usually” is not the contract your CFO wants to hear.
One paraphrased idea from Werner Vogels (Amazon CTO): you build systems assuming things will fail, then design so the blast radius is small and recovery is routine.
Fast diagnosis playbook (what to check first/second/third)
This is the order that gets you back fastest in real production. The goal is not to understand everything. The goal is to restore checkout, then do the forensics.
First: confirm it’s a PHP fatal and capture the signature
- Check the web server error log (Nginx/Apache) and PHP-FPM log for a fresh fatal around the incident time.
- Look for the top stack frame pointing to
wp-content/plugins/orwp-content/themes/. - If you can’t see logs, enable WordPress debug logging safely (log to file, not display).
Second: remove variables by disabling the most likely offender
- Disable the last-updated plugin(s) first.
- If you don’t know which changed, disable all plugins via WP-CLI or rename plugin directories.
- Switch to a default theme (Storefront/Twenty Twenty-*) if the fatal points into the theme.
Third: verify database health and whether migrations ran
- Check whether WooCommerce is prompting for database updates, whether scheduled actions are stuck, and whether options/transients are corrupted.
- Confirm DB connectivity and replication status if applicable.
- Take a snapshot/backup before running any “database update” button.
When to stop and restore from backup
If the site is down and you can’t isolate the fatal in 15–30 minutes, restore to the last known good snapshot. Then debug on staging. Hero debugging in production is how you become a cautionary tale.
Stabilize first: stop the bleeding without making it worse
Recovery starts with stabilizing the system, because broken systems attract “quick fixes” that create secondary incidents. Your first job is to prevent data damage:
- Freeze change: pause deployments, disable auto-updates, stop “helpful” coworkers from clicking buttons.
- Preserve evidence: keep logs, copy stack traces, record versions.
- Protect orders: if checkout is broken but admin works, consider putting the store in maintenance mode with a clear banner, not a 500 error.
- Back up now: even if you already have backups, take a fresh snapshot before you roll anything back. You might need to recover orders created during the outage window or partial migrations.
Short joke #1: Auto-updates are like “surprise refactors” you didn’t schedule—exciting for exactly nobody on call.
Logs and signals that matter (and the ones that lie)
WordPress failures are noisy. You need clean signals.
High-signal artifacts
- Web server error log: tells you whether PHP died, timeouts occurred, or upstreams failed.
- PHP-FPM log: catches fatals, memory exhaustion, and worker crashes.
- WordPress debug.log: can capture plugin warnings and fatal traces if enabled.
- WooCommerce status logs: sometimes includes migration issues and REST failures.
- Database error log: deadlocks, disk full, corrupted tables.
Low-signal distractions
- Browser console errors: useful for broken JS checkout, not for PHP critical errors.
- Cache HIT ratios: during an outage, caches can mask the blast radius or keep serving broken pages reliably.
- “It worked on my machine”: local environments rarely match production PHP extensions, memory limits, or file permissions.
One recurring trick: a “critical error” that appears only for some users can be caused by page caching serving a cached error page, or by different PHP pools/servers running different code. Treat inconsistency as a deployment hygiene problem first.
Rollback strategy: plugin/theme/core without corrupting data
Rollback isn’t one thing. Decide what you’re rolling back and what state you need to preserve.
1) Roll back a plugin (WooCommerce or another)
If a plugin update triggered the fatal, rolling back just that plugin is usually safest. But consider this detail: if the plugin performed a database migration, rolling back code might make the old code choke on the new schema. WooCommerce is generally careful about backwards compatibility, but extensions vary wildly.
Rule of thumb: roll back code first to restore page rendering, then assess the database migration status before rolling forward again.
2) Switch theme to isolate theme-level fatals
A theme calling removed WooCommerce template functions is common after WooCommerce updates. Switching to Storefront (or a default WP theme) is a surgical way to confirm theme involvement. You can keep plugins running and bring checkout back while your dev team fixes the theme.
3) Roll back WordPress core (rarely required, but possible)
Core updates can surface latent incompatibilities. Rolling back core is riskier because plugin compatibility expects a forward direction. I only do it if (a) the incident clearly started with core update, (b) the environment is otherwise stable, and (c) I have a known good snapshot to restore.
4) Full restore from snapshot
For stores with meaningful traffic, “full restore” is often the fastest safe path—if you have disciplined snapshotting. Restore code + database to a known good point, bring the site up, then replay the missing orders if needed. The key is understanding your Recovery Point Objective (RPO): how much data you’re willing to lose.
Database recovery: how to avoid turning a PHP error into a revenue event
Most WooCommerce “critical errors” are code-level. The database is often fine. Don’t make it not fine.
What can go wrong with the database during an update
- Schema drift: new columns/tables created, old code not expecting them (usually okay), or new code expecting them but they weren’t created due to a failed migration.
- Options corruption: a serialized option updated with incompatible structure; PHP then fatals on unserialize or array access.
- Action Scheduler backlog: WooCommerce uses Action Scheduler for background jobs. If it jams (DB locks, timeouts), the site may behave “broken” in odd ways.
- Character set/collation surprises: rare, but upgrades can make strict SQL modes matter more, revealing bad queries in extensions.
Database safety rules during recovery
- Snapshot before you click “Run database update.” Always. No exceptions.
- Prefer read-only diagnosis queries first. Verify table presence, row counts, recent order writes.
- Don’t “repair tables” as a reflex. It’s sometimes needed, but it’s also a great way to destroy evidence and create new problems.
- Understand what your backup includes. Some “backups” skip transient tables or large tables. WooCommerce orders live in posts/postmeta (or HPOS tables if enabled). Make sure your backup covers what pays you.
Practical tasks: 12+ real commands, outputs, and decisions
These tasks assume you have SSH access to the server and a standard Linux + Nginx/Apache + PHP-FPM + MySQL/MariaDB stack. Adjust paths for your distro. Each task includes: command, sample output, what it means, and the decision.
Task 1: Confirm current incident symptoms (HTTP status and response)
cr0x@server:~$ curl -I -s https://store.example.com/ | head
HTTP/2 500
date: Fri, 27 Dec 2025 10:11:22 GMT
content-type: text/html; charset=UTF-8
server: nginx
What it means: It’s a server-side failure, not just a broken asset or JS error.
Decision: Go straight to server/PHP logs. Don’t waste time in the browser.
Task 2: Find the fatal error in Nginx error log
cr0x@server:~$ sudo tail -n 60 /var/log/nginx/error.log
2025/12/27 10:11:19 [error] 22190#22190: *8841 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: Call to undefined function wc_get_logger() in /var/www/html/wp-content/plugins/some-gateway/inc/init.php:41
Stack trace:
#0 /var/www/html/wp-settings.php(453): include_once()
#1 /var/www/html/wp-config.php(90): require_once('...')
#2 /var/www/html/wp-load.php(50): require_once('...')
#3 /var/www/html/wp-blog-header.php(13): require_once('...')
#4 /var/www/html/index.php(17): require('...')
#5 {main}
thrown in /var/www/html/wp-content/plugins/some-gateway/inc/init.php on line 41" while reading response header from upstream, client: 198.51.100.19, server: store.example.com, request: "GET / HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.1-fpm.sock:", host: "store.example.com"
What it means: A payment gateway plugin called a WooCommerce function that isn’t loaded (or WooCommerce itself is broken/disabled/half-updated).
Decision: Disable that gateway plugin first. If WooCommerce itself updated, confirm WooCommerce loads cleanly.
Task 3: Check recent package/file changes (what updated?)
cr0x@server:~$ ls -lt /var/www/html/wp-content/plugins | head
total 92
drwxr-xr-x 10 www-data www-data 4096 Dec 27 10:02 woocommerce
drwxr-xr-x 8 www-data www-data 4096 Dec 27 10:02 some-gateway
drwxr-xr-x 7 www-data www-data 4096 Nov 18 09:40 wp-mail-smtp
What it means: WooCommerce and the gateway were touched at the same time—likely the update window.
Decision: Disable the gateway first (fast), then validate WooCommerce loads. If still broken, roll back WooCommerce.
Task 4: Disable one plugin fast by renaming its directory
cr0x@server:~$ cd /var/www/html/wp-content/plugins
cr0x@server:~$ sudo mv some-gateway some-gateway.disabled
cr0x@server:~$ curl -I -s https://store.example.com/ | head
HTTP/2 200
date: Fri, 27 Dec 2025 10:13:01 GMT
content-type: text/html; charset=UTF-8
server: nginx
What it means: The gateway plugin caused the fatal. The site is serving pages again.
Decision: Keep it disabled, then find a compatible plugin version or vendor patch before re-enabling. Verify checkout specifically.
Task 5: Validate checkout endpoint returns 200 (not just homepage)
cr0x@server:~$ curl -I -s https://store.example.com/checkout/ | head
HTTP/2 200
date: Fri, 27 Dec 2025 10:13:19 GMT
content-type: text/html; charset=UTF-8
server: nginx
What it means: Checkout route renders at HTTP level. Not a guarantee of payment success, but you’re out of the ditch.
Decision: Proceed to functional validation (add-to-cart, shipping calc, payment method availability) and monitor logs.
Task 6: If WP-CLI is available, list plugins and confirm what’s active
cr0x@server:~$ cd /var/www/html
cr0x@server:~$ sudo -u www-data wp plugin list --status=active
+-------------------+--------+-----------+---------+
| name | status | update | version |
+-------------------+--------+-----------+---------+
| woocommerce | active | available | 9.3.2 |
| akismet | active | none | 5.3 |
| wp-mail-smtp | active | none | 4.3.1 |
+-------------------+--------+-----------+---------+
What it means: The problematic gateway is no longer active (good). WooCommerce itself is active, but shows an update available, which can hint at partial upgrade workflows.
Decision: Do not update anything else yet. Capture state, then decide whether to roll WooCommerce forward to a stable version on staging.
Task 7: Enable WordPress debug logging safely (no on-screen errors)
cr0x@server:~$ sudo -u www-data wp config set WP_DEBUG true --raw
cr0x@server:~$ sudo -u www-data wp config set WP_DEBUG_LOG true --raw
cr0x@server:~$ sudo -u www-data wp config set WP_DEBUG_DISPLAY false --raw
cr0x@server:~$ sudo -u www-data wp config set SCRIPT_DEBUG false --raw
What it means: Errors will be logged to wp-content/debug.log without exposing stack traces to customers.
Decision: Use this temporarily during incident response; remove or revert after stabilization to reduce noise and disk usage.
Task 8: Read WordPress debug log and identify follow-on warnings
cr0x@server:~$ sudo tail -n 80 /var/www/html/wp-content/debug.log
[27-Dec-2025 10:13:25 UTC] PHP Warning: Undefined array key "country" in /var/www/html/wp-content/plugins/woocommerce/includes/class-wc-countries.php on line 133
[27-Dec-2025 10:13:26 UTC] PHP Notice: Function wpdb::prepare was called incorrectly. The query does not contain the correct number of placeholders. in /var/www/html/wp-includes/class-wpdb.php on line 1777
What it means: The fatal is gone, but you have compatibility warnings. They can become fatals under stricter PHP versions or future releases.
Decision: Track these as tech debt; prioritize any warnings tied to checkout/taxes/shipping.
Task 9: Verify PHP version and loaded modules (compatibility check)
cr0x@server:~$ php -v
PHP 8.1.27 (cli) (built: Nov 20 2025 12:12:11) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.27, Copyright (c) Zend Technologies
with Zend OPcache v8.1.27, Copyright (c), by Zend Technologies
What it means: You’re on PHP 8.1 with OPcache. Some older plugins still break here, especially around deprecated functions.
Decision: If the failing plugin is old, rolling it back may not help; you may need a vendor-supported version compatible with PHP 8.1+.
Task 10: Clear PHP-FPM gracefully to flush OPcache (if you suspect stale code)
cr0x@server:~$ sudo systemctl reload php8.1-fpm
cr0x@server:~$ sudo systemctl status php8.1-fpm --no-pager | head -n 12
● php8.1-fpm.service - The PHP 8.1 FastCGI Process Manager
Loaded: loaded (/lib/systemd/system/php8.1-fpm.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2025-12-27 08:03:10 UTC; 2h 10min ago
Docs: man:php-fpm8.1(8)
What it means: Reload succeeded; workers will restart gracefully and refresh OPcache state.
Decision: If problems vanish after reload, your “update” may have been a cache coherency issue. Fix the deployment procedure to reload PHP-FPM after code changes.
Task 11: Check disk space (updates fail weirdly when you’re out of it)
cr0x@server:~$ df -h /var/www/html | tail -n 1
/dev/vda1 40G 39G 1.1G 98% /
What it means: You’re nearly full. WordPress updates can partially apply when writes fail, leaving a Frankenstein plugin directory.
Decision: Free space before attempting any re-update or rollback. If the plugin directory timestamps look inconsistent, consider restoring from backup rather than trusting the filesystem.
Task 12: Confirm file ownership and permissions (to avoid partial updates)
cr0x@server:~$ stat -c "%U:%G %a %n" /var/www/html/wp-content/plugins/woocommerce | head -n 1
www-data:www-data 755 /var/www/html/wp-content/plugins/woocommerce
What it means: Ownership aligns with the web user. If you see root:root or mismatched perms, the updater may fail writing files.
Decision: Fix ownership before rerunning updates; otherwise you’re signing up for repeat outages.
Task 13: Check MySQL connectivity and basic health
cr0x@server:~$ mysqladmin -uroot -p ping
Enter password:
mysqld is alive
What it means: DB is reachable and responding.
Decision: Proceed with targeted queries; don’t assume DB corruption if the issue was a PHP fatal.
Task 14: Verify recent orders are still writing (read-only confirmation)
cr0x@server:~$ mysql -uroot -p -e "USE wordpress; SELECT ID, post_date, post_status FROM wp_posts WHERE post_type='shop_order' ORDER BY ID DESC LIMIT 5;"
Enter password:
+-------+---------------------+------------+
| ID | post_date | post_status|
+-------+---------------------+------------+
| 81231 | 2025-12-27 10:05:41 | wc-pending |
| 81230 | 2025-12-27 09:58:10 | wc-completed |
| 81229 | 2025-12-27 09:41:03 | wc-processing |
| 81228 | 2025-12-27 09:30:55 | wc-failed |
| 81227 | 2025-12-27 09:22:14 | wc-completed |
+-------+---------------------+------------+
What it means: Orders exist during the incident window (pending/failed may be expected if checkout broke mid-flow).
Decision: Coordinate with support: identify customers affected and reconcile payments. Do not purge “failed” orders until you understand gateway behavior.
Task 15: Switch theme via WP-CLI (quick isolation)
cr0x@server:~$ sudo -u www-data wp theme list --status=active
+-----------+--------+---------+
| name | status | version |
+-----------+--------+---------+
| my-theme | active | 3.1.0 |
+-----------+--------+---------+
cr0x@server:~$ sudo -u www-data wp theme activate storefront
Success: Switched to 'Storefront' theme.
What it means: You can bypass theme fatals without touching plugins.
Decision: If the site comes back with Storefront, your theme is the problem. Keep Storefront temporarily and fix your theme in a controlled rollout.
Task 16: If WP-CLI is unavailable, disable all plugins by renaming the plugins directory
cr0x@server:~$ cd /var/www/html/wp-content
cr0x@server:~$ sudo mv plugins plugins.off
cr0x@server:~$ sudo mkdir plugins
cr0x@server:~$ sudo chown www-data:www-data plugins
What it means: WordPress will treat plugins as absent. This is the blunt instrument that gets the admin UI back.
Decision: Use this when you can’t identify the offender quickly. Bring the site up, then reintroduce plugins one-by-one (or in batches) to find the culprit.
Task 17: Validate WooCommerce database update status (Action Scheduler backlog hint)
cr0x@server:~$ sudo -u www-data wp option get woocommerce_db_version
9.3.2
cr0x@server:~$ sudo -u www-data wp option get woocommerce_version
9.3.2
What it means: Code version and DB version match. That reduces the chance you’re in a half-migrated state.
Decision: Focus on extension compatibility rather than DB recovery—unless you see missing tables or stuck background jobs.
Three corporate mini-stories from the trenches
Mini-story 1: The outage caused by a wrong assumption
The company: a mid-sized retailer with a WooCommerce store that does steady daily volume, plus a few seasonal spikes. They had a decent hosting provider and a decent team. Not a “move fast and break things” shop. More like “move carefully and still break things, but with meetings.”
An engineer updated WooCommerce and a handful of extensions during a quiet weekday. The assumption: “If the plugin update screen says it’s compatible with our WordPress version, it’s compatible with our environment.” That assumption is the seed of many outages.
In their environment, PHP had recently been upgraded by the host from 7.4 to 8.1. Nobody tied it to the store, because the site had been “fine” for weeks. The gateway plugin update introduced a code path using a deprecated behavior that PHP 8.1 treated more strictly. Not every page hit it. Checkout did, under specific cart conditions.
The team chased WooCommerce templates, then caching, then “maybe Stripe is down.” Meanwhile, customers could browse but couldn’t pay, which is the most expensive kind of “mostly up.” The eventual fix was embarrassingly simple: roll back the gateway plugin and pin it to a vendor-supported version.
What they changed afterward was more important than the fix: they added a pre-update environment report (PHP version, extensions, memory limit) and stopped trusting compatibility banners as a substitute for testing. Compatibility banners are marketing, not contracts.
Mini-story 2: The optimization that backfired
Different company, similar stack. Their performance consultant had tuned caching aggressively: full-page cache at the edge, object cache in Redis, OPcache dialed up, and a deployment process that “only changes what’s necessary.” Translation: code updates didn’t restart PHP-FPM because “it’s faster.”
They updated WooCommerce. Files changed. The edge cache purged correctly. But OPcache kept serving old bytecode for some files while new files existed on disk for others. A classic split-brain between “what the filesystem says” and “what PHP is actually executing.” The result was a fatal involving missing class methods that absolutely did exist… in the new code, not the cached bytecode.
They tried rolling back the plugin by copying old files back. That made it worse because OPcache now had a chaotic mixture of old and new bytecode versions. Every refresh was a new surprise. The team described it as “haunted.” I described it as “predictable, just not to you.”
The fix was to reload PHP-FPM, clear OPcache coherently, and then deploy using an atomic release pattern (new directory, symlink switch) paired with a controlled reload. Performance was still fine. And now updates didn’t involve séance rituals.
They learned the hard way: optimizations that skip restarts are fine until they aren’t. Then they turn into downtime multipliers.
Mini-story 3: The boring but correct practice that saved the day
This one is less dramatic, which is the point. A B2B seller ran WooCommerce with a small set of carefully chosen extensions. They had a staging environment that mirrored production: same PHP version, same object cache, same theme, and a scrubbed copy of the production database refreshed weekly.
Before updates, they ran a checklist: snapshot production, update staging, run a small test suite (login, add-to-cart, checkout with test gateway, admin order edit), then schedule production updates during a low-traffic window. Nothing fancy. Just consistent.
One update still went sideways: a shipping extension update introduced a fatal when certain address formats were entered. But staging caught it. They paused that extension update, updated everything else, and pushed production safely.
The “savings” wasn’t just avoiding downtime. It was avoiding the panic tax: emergency meetings, late-night restores, and the slow bleed of customer trust. Their practice was boring, and it worked. Most reliability is boring. That’s why it’s rare.
Interesting facts and historical context
A little context helps you predict failure modes instead of reacting to them.
- WooCommerce started as a plugin built by WooThemes and later became part of Automattic’s ecosystem, which influenced its release cadence and integration patterns.
- WordPress introduced the “critical error” screen to reduce information leakage from fatals and guide admins via email recovery links, shifting troubleshooting from “white screen” to logged recovery.
- The classic “White Screen of Death” era wasn’t just drama—it was often PHP fatals with display_errors off, forcing admins to learn log-first workflows.
- WooCommerce uses Action Scheduler (also used by other plugins) for background processing; when it jams, the symptoms look like “WooCommerce is broken” even if the frontend renders.
- PHP 8.x tightened behavior around notices and deprecated patterns, so plugins that “worked for years” can suddenly fail after a server upgrade even before a code upgrade.
- WordPress updates are usually atomic at the package level, not at the filesystem level; if disk fills up mid-update, you can end up with partial directories and missing files.
- OPcache was built to speed PHP dramatically, but it introduced a new class of failure: stale bytecode after deploys if you don’t reload workers.
- WooCommerce has evolved its data storage model over time (including optional high-performance order storage); migrations can be safe but still need rollback planning.
Common mistakes: symptom → root cause → fix
This section is intentionally specific. Generic advice is how you get repeat incidents.
1) Symptom: “Critical error” immediately after updating a payment/shipping extension
Root cause: Extension calls WooCommerce functions before WooCommerce loads, or depends on a newer WooCommerce API than you have, or breaks on your PHP version.
Fix: Disable the extension by renaming its directory. Restore site. Then install a compatible extension version on staging and re-enable.
2) Symptom: Site works on one server but not another (behind a load balancer)
Root cause: Partial deploy across nodes, mismatched plugin files, or different PHP-FPM/OPcache state.
Fix: Verify release versions across all nodes, then reload PHP-FPM everywhere. Use atomic deployments and consistent cache invalidation.
3) Symptom: Admin works, frontend 500s
Root cause: Theme-level fatal (template override, removed hook), or a plugin that only runs on frontend requests.
Fix: Switch theme to Storefront; if fixed, patch theme overrides. If not, disable frontend-heavy plugins (caching, optimization, page builders) first.
4) Symptom: “Critical error” appears, then disappears after a few minutes
Root cause: Transient cache inconsistency, OPcache clearing slowly, background job finishing, or rolling restarts.
Fix: Don’t declare victory. Reload PHP-FPM, clear caches coherently, and monitor logs for recurring fatals. Intermittent is still broken; it’s just better at hiding.
5) Symptom: Update screen hangs; afterward the site is broken with missing files
Root cause: Disk full, permissions wrong, or network interruption mid-update leading to incomplete plugin/core files.
Fix: Free disk space and restore from a known-good snapshot. Don’t try to “patch” missing files manually unless you enjoy archaeology under pressure.
6) Symptom: Checkout loads but payments fail or orders stuck pending
Root cause: Gateway plugin disabled/rolled back, webhook endpoints changed, or Action Scheduler backlog preventing order completion tasks.
Fix: Verify gateway plugin status and webhook logs; check Action Scheduler queues; reconcile pending orders with payment provider.
7) Symptom: After rollback, WooCommerce asks to run database updates again
Root cause: Code/DB version mismatch; rollback took code back but DB version remains forward, or the update didn’t finish.
Fix: Restore DB snapshot matching the code, or move code forward to match the DB. Don’t keep flip-flopping versions; pick a consistent pair.
Checklists / step-by-step plan (production-safe)
Incident response checklist (first 30 minutes)
- Confirm impact: homepage + checkout + admin. Capture HTTP status.
- Freeze changes: pause auto-updates and deployments until stable.
- Grab the fatal signature: web server + PHP-FPM logs around the incident time.
- Snapshot now: filesystem + database snapshot/backup, even if you plan to roll back.
- Disable last-changed plugin: rename directory; re-test.
- If unclear: disable all plugins; re-test; then restore plugins selectively.
- If theme suspected: switch to Storefront; re-test checkout.
- Flush coherently: reload PHP-FPM (OPcache), purge full-page cache carefully.
- Validate orders: ensure order creation still works; identify stuck statuses.
- Communicate: status page/internal comms: what broke, what’s mitigated, what’s next.
Safe rollback checklist (plugin-focused)
- Record plugin version before rollback (from directory readme or WP-CLI).
- Confirm disk space and permissions are sane.
- Disable plugin (rename dir) to restore service fast.
- Restore a previous plugin version from your artifact store/backup (not from random copies).
- Reload PHP-FPM to avoid stale OPcache.
- Re-enable plugin and test critical flows in a controlled way.
- Monitor logs for 15–30 minutes after restoration.
Safe restore checklist (full snapshot restore)
- Identify the last known good restore point and the outage start time.
- Decide on RPO: do you accept losing orders between restore point and now?
- Export orders created after the restore point if possible (or plan manual reconciliation).
- Restore database snapshot first (or in a consistent pair with filesystem snapshot).
- Restore filesystem (wp-content, plus core if you snapshot it) matching that DB.
- Reload PHP-FPM and web server.
- Validate checkout end-to-end with test transactions.
- Reconcile orders/payments for the missing window.
Short joke #2: The only thing worse than no backup is discovering your “backup” is a motivational poster with a ZIP icon.
Prevention: keep updates from taking you down again
Once you’ve recovered, the temptation is to exhale and move on. Resist that. Recovery without prevention is just scheduling your next outage.
1) Run updates in staging that actually matches production
A staging site that runs PHP 7.4 while production runs 8.1 is not staging. It’s theater. Match:
- PHP version and extensions
- Database engine/version and SQL mode
- Object cache (Redis/Memcached) behavior
- OPcache settings
- Theme and must-use plugins
2) Treat WooCommerce updates as “application releases”
WooCommerce isn’t a contact form plugin. It’s your revenue engine. That means:
- Maintenance windows for major updates
- Change logs reviewed like release notes, not like a newsletter
- Roll-forward and rollback plans documented
- Post-update verification scripts (smoke tests) run every time
3) Control version drift and remove plugin roulette
Too many stores run a “plugin marketplace” in production: 40+ plugins, each with its own release schedule and support quality. The failure rate is predictable. Reduce it:
- Remove plugins you don’t absolutely need.
- Prefer well-maintained vendors with clear compatibility statements.
- Pin versions and update in batches with known-good combinations.
4) Make deployments atomic and cache-aware
If you update code, you must control:
- Filesystem atomicity: deploy to a new directory then switch a symlink, or otherwise avoid partial file states.
- OPcache consistency: reload PHP-FPM after deploy, or use a safe cache invalidation mechanism.
- Edge/full-page cache purges: purge after deploy, not before, and avoid caching error responses.
5) Monitor the right things
If you only monitor “HTTP 200 on homepage,” you’ll miss the expensive failures. Monitor:
- Checkout endpoint success rate
- Order creation rate and payment completion rate
- PHP fatal count in logs (alert on spikes)
- Database deadlocks/timeouts
- Queue backlogs (Action Scheduler)
FAQ
1) Should I roll back WooCommerce or the extension that updated?
Roll back (or disable) the extension first if the fatal stack trace points into it. WooCommerce is the platform; extensions are the usual offenders. If the fatal is inside WooCommerce core files, then consider rolling WooCommerce back or restoring from snapshot.
2) Can I fix the “critical error” by disabling all plugins?
Yes, and it’s often the fastest isolation method. It’s disruptive, but it gets you a working admin UI. Then re-enable plugins in batches until you find the offender. Do it methodically, not emotionally.
3) Why did the update succeed in the dashboard but the site broke?
The dashboard update flow can complete even if some files fail to write cleanly, especially with low disk space or permission issues. Also, a plugin can update successfully but still be incompatible with your PHP version or another plugin. “Installed” is not the same as “works.”
4) Do I need to run WooCommerce database updates after an update?
Sometimes, yes. But take a snapshot first. If you already rolled back code, don’t run forward migrations on a rolled-back codebase. Keep code and DB versions aligned.
5) What if I can’t access wp-admin to disable plugins?
Rename the plugin directory over SSH (wp-content/plugins → plugins.off) or rename the suspected plugin folder. That forces WordPress to treat plugins as inactive without needing wp-admin.
6) Can caching cause a “critical error”?
Caching usually doesn’t cause the fatal, but it can amplify it (serving cached error pages) or make it intermittent (different servers, different OPcache state). Clear caches coherently and reload PHP-FPM after code changes.
7) After disabling the broken plugin, checkout works but payments don’t. What now?
That’s expected if the payment gateway plugin is the broken one. Restore service first (even if it’s “browse-only”), then pick a compatible gateway version and validate webhooks. Meanwhile reconcile pending orders with your payment provider logs.
8) Is it safe to restore only files and not the database?
Sometimes. If you’re confident no database migration ran and orders are flowing, a code-only rollback can be safe. If WooCommerce or an extension might have changed schema/options, restore code and DB as a consistent pair or accept you’re doing a science experiment.
9) What’s the fastest way to identify the offending plugin?
The fatal stack trace usually names it. Look for paths under wp-content/plugins/ in logs. If logs are unavailable, disable all plugins, then re-enable them until the error returns. That’s crude, but it’s reliable.
10) Should I leave WP_DEBUG on after I fix it?
No. Turn it off (or at least disable logging) once you’re stable, unless you have log rotation and a reason. Debug logs grow, and disks fill. Disks filling is how “minor warnings” become “major outages.”
Conclusion: next steps you can do today
If your WooCommerce store threw a critical error after an update, the winning move is boring and repeatable:
- Get the fatal signature from server/PHP logs. Don’t guess.
- Disable the offender (usually an extension) to restore service fast.
- Reload PHP-FPM to avoid OPcache weirdness after code changes.
- Validate checkout and order writes, not just the homepage.
- Only then do the deeper work: staging reproduction, version pinning, and prevention.
And tomorrow—when nobody is yelling—build the safety rails: production-like staging, snapshots before updates, atomic deployments, and monitoring that understands your business (orders) not just your servers (pings). That’s how you make WooCommerce updates boring again.