If your server experiences slow queries, use the provided documentation to identify and resolve these issues. Tools and guides are available to help parse slow query logs and understand how to improve query performance. To request help for severely-impacted production sites, create a Support ticket with critical urgency for immediate assistance or to terminate problematic queries on your behalf.
Cloud Platform replaces all HTTP 500, 501, 502, 503 and 504 status code responses served to visitors of your production environments with a generic 503 Service Unavailable response. Displaying the following common response prevents the production environment from leaking error message information:
Temporarily Unavailable
The website that you're trying to reach is having technical difficulties
and is currently unavailable. We are aware of the issue and are working
hard to fix it. Thank you for your patience.
To assist with troubleshooting during development, non-production environments pass all HTTP 5xx status codes through the load balancers back to the requesting client without any replacement. You can review these error messages in your log files, which you can access using the following methods:
For production environments, logs and log streaming should be used to determine the root cause. Access logs show the real HTTP status code at the backend, and matching logs from other sources (PHP Errors, Drupal Watchdog, and so on) can be found with the X-Request-Id value, which matches all logged items for the same request.
Common causes of "Temporarily Unavailable" pages on production environments include:
- Transitory resource limits such as insufficient CPU or DB resources, etc. due to high traffic (either expected, or from unusual robot crawling or DDoS attacks) and/or application complexity.
- Code and/or data changes or bugs that trigger PHP exceptions or errors.
Resolution varies depending upon the situation, and may include actions such as rollback changes to a site (for example, restoration of an older configuration or code and/or a database backup), PHP memory limit adjustments, or use of a Web Application Firewall (WAF) to block traffic through Acquia Edge or other methods.
To learn more about how your infrastructure allocates resources, visit Tuning your infrastructure configuration.