Synthetic 503 errors in VCL

If a fatal error occurs in your service while processing your VCL logic, Fastly will generate an error response with a 503 HTTP status, instead of using a response from an upstream server or cache, and unless intercepted by code running in vcl_error, this generated error may be served to the end user.


This is a companion discussion topic for the original entry at https://developer.fastly.com/learning/vcl/errors