Incorrect use of 503 status code #11512
Description
More generally, Magento appears to use the "503 (service unavailable)" status code when an "unexpected error" happens. This ranges, but a good example of such an event is anything that generates the "report" format pages.
The problem is, this status code is generally reserved for cases in which the server is suffering a temporary problem[1][2]. When the server is in an error case, I would have expected something such as a 500 (internal server error) to be expressed, clearly indicating an "abnormal" event, or one that is not an expected failure mode.
This has implications for monitoring. When setting up alerting rules, it's unclear how to express that a problem is temporary in nature. For example, if during a period of high traffic there are several 503s, this does not warrant immediate resolution. However, if there is a spike in 503s as a result of an SQL constraint issue, this requires immediate attention, and will not self-resolve.
I would suggest modifying the report page to return a 500, rather than a 503. Additionally, some guidelines as to what status code was used when would be useful.
[1] - https://stackoverflow.com/questions/2786595/what-is-the-correct-http-status-code-to-send-when-a-site-is-down-for-maintenance
[2] - https://en.wikipedia.org/wiki/List_of_HTTP_status_codes