# Critical Error "There has been a critical error on this website." is WordPress's own message when your website crashes: a PHP error stopped it before it could answer the POS. The fault is on the website, not on the till. The till may hold changes your store doesn't have yet, so don't clear its data while the website is being fixed. ## At the till[​](#at-the-till "At the tillへの直接リンク") Don't clear this till's data The error's entry in Logs says so too: "Don't clear this device's data — it may hold changes your store doesn't have yet." Clearing it loses them. If one more try below still fails, wait for the website to be fixed. **Taking a payment?** Don't charge again yet. Follow the page for the checkout code in the message: * [CHECKOUT101](/ja/error-codes/CHECKOUT101.md): the cart is safe to try again. * [CHECKOUT201](/ja/error-codes/CHECKOUT201.md): the sale may have gone through. For anything else: 1. Try the action once more. A crash can be a one-off. 2. If it fails again, open **Store health** from the pulse icon at the foot of the menu, then **Logs**, and press **Errors**. 3. Tap the **SYNC131** entry to open it. It tells you whether your data is safe, and **Help — SYNC131** opens the code's page. 4. Press **Copy debug info** and send it, with the time it happened, to whoever looks after your website. ![Store health on the Logs tab: the pulse icon in the menu, the Logs tab, errors today, the Errors filter, the search field and Copy debug info](/img/2.x/support/troubleshooting/critical-error/en/tablet-light-regular--ce-1-logs.png)123456 1. **Store health** — the pulse icon at the foot of the menu. A red number on it counts new errors. 2. **Logs** — everything this till did, kept for 30 days. 3. **errors today** — errors logged today. Here there are none. 4. **Errors** — shows only errors. A critical error is an entry with **SYNC131** in its **Status** column. 5. **Search Logs** — find an entry by its words or its code, such as SYNC131. 6. **Copy debug info** — copies a report for support. In the phone and tablet apps it's **Share debug info**. ## Where you see it[​](#where-you-see-it "Where you see itへの直接リンク") * **On the till**, as a message after the action that failed, with the code [SYNC131](/ja/error-codes/SYNC131.md): your store had an error and didn't finish the request. * **In the store's own reason**, where the POS shows one, such as at checkout or on a change your store refused. The reason is WordPress's sentence, or the PHP error itself when your website shows error details, such as *Allowed memory size of 134217728 bytes exhausted in wp-includes/class-wpdb.php:2324*. * **At checkout**, the message carries a checkout code instead, which says what happened to the payment: [CHECKOUT101](/ja/error-codes/CHECKOUT101.md) when the cart is safe to try again, [CHECKOUT201](/ja/error-codes/CHECKOUT201.md) when the POS can't tell whether the sale went through. Follow that page before you charge again. * **In a browser**, when the website crashes while the POS page itself loads. WordPress shows its own error page in place of the POS. * **In Store health → Logs**, as an error entry with **SYNC131** in the **Status** column. ## Find the cause on your website[​](#find-the-cause "Find the cause on your websiteへの直接リンク") This part needs someone who can sign in to WP Admin. 1. Go to **WooCommerce → Status → Logs** and open the newest **fatal-errors** log from around the time of the failure. A crash almost always leaves its PHP error there. 2. Read the first line of the error and the file it names. A file under `wp-content/plugins/` names the plugin it belongs to; one under `wp-content/themes/` names the theme. 3. If the crashes started after a plugin or theme update, undo that update or deactivate the plugin or theme. If they started after a PHP upgrade, ask your host to check that change. [Plugin Conflicts](/ja/troubleshooting/common-problems/plugin-conflicts.md) shows how to find the plugin at fault. 4. Nothing in WooCommerce's logs? WooCommerce's guide [Finding PHP error logs](https://woocommerce.com/document/finding-php-error-logs/) shows where else to look, or ask your host for the server's PHP error log for the same time. 5. Once it's fixed, go back to the till. For a payment, check the checkout code's page before you charge again. For anything else, try the action again. **WP Admin > POS > Settings**, **Logs** under **Tools**, shows **Fatal errors detected — view in WooCommerce logs** whenever WooCommerce has written a fatal-errors log file. The link opens WooCommerce's logs filtered to fatal errors. The email from WordPress When a plugin or theme causes the crash, WordPress emails the site's admin address: **Your Site is Experiencing a Technical Issue**. Its link opens WP Admin in recovery mode once you sign in, where you can deactivate the plugin at fault even when WP Admin won't open normally. ### Errors you may find[​](#common-errors "Errors you may findへの直接リンク") **Allowed memory size of … bytes exhausted.** PHP ran out of memory. Ask your host to raise PHP's memory limit. **An error in another plugin's file.** Some plugins are known to clash with the POS. Look for it under [Known plugin conflicts](/ja/troubleshooting/common-problems/plugin-conflicts.md#known-plugin-conflicts), with its fix. **A fatal error or *Cannot modify header information* after you remove the free plugin and upload Pro.** Pro doesn't need the free plugin: it carries the free plugin's code and runs on its own, so you don't need to put the free plugin back. Read the error's first line and the file it names, as above. If WP Admin shows **WCPOS Pro failed to load. Please run composer install.**, the zip is missing part of Pro: download it again from your [Downloads](https://wcpos.com/account/downloads) and upload that. See [Install the Pro plugin](/ja/getting-started/pro-license.md#installation). ## Get help[​](#get-help "Get helpへの直接リンク") Send us the error's first line from the log, or the debug info from the till, on Discord or by email: [Discord Community](https://wcpos.com/discord) With WCPOS Pro A Pro licence comes with priority support in the Pro channels on Discord. Connect your Discord account to your licence to open them: see [Where to ask](/ja/troubleshooting/contact-support.md#where-to-ask). ## Related Documentation[​](#related-documentation "Related Documentationへの直接リンク") [SYNC131Your store had an error and didn't finish the request](/ja/error-codes/SYNC131.md) [Store HealthLogs, Copy debug info and what's waiting to send](/ja/troubleshooting/store-health.md) [Plugin ConflictsFind the plugin that breaks your website](/ja/troubleshooting/common-problems/plugin-conflicts.md)