Quote:
Originally Posted by JSWolf
But I have gotten a 504 error before from Overdrive and the solution was to delete the Overdrive cookies.
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Unless the cookie was triggering the overdrive.com website to act as a gateway on your behalf that it wouldn't do absent the cookie, the 504 error going away would have been pure coincidence.
e.g., Say the cookie contained your login credentials for my_library, without those credentials my_library would not do a database query for you. And if the database being down was the original problem, you have effectively stopped my_library from trying to access that database for you. The 504 may go away, but you are not in any better situation than you were before. Trying a database query and failing is not any better from your viewpoint than never trying the database query in the first place.
But despite this example of how a cookie might uncover a 504 error, it was probably just pure coincidence that you deleting the cookie appeared to make a difference. It was probably a short term transient error due to overload that caused the 504 (which is what many of them are), and the time it took you to delete the cookie allowed the transient condition to clear on its own.
But I'm just speculating on the most likely cause based on my work experience. We can't know for sure what happened without a look at the relevant log files on the server. I have noticed slowness on the Overdrive website quite often. This is most noticeable to me when I have Overdrive searching all my libraries to find a copy of the book I want. This manifestation of slowness strongly points to an overload condition. It could well be that Overdrive is chronically underpowered for the task it's being asked to do. This may result in overall slowness, partial webpage renderings, timeouts, and various other apparently unrelated error messages. Developers sometimes throw specific error conditions into a generic pool (because they are not adequately looking for them), and spit out a cryptic error message that doesn't really address the true problem - something like "unknown failure". A useless message. Sometimes they even try to deflect blame by intentionally constructing an error message that appears to indict the user, and not the server that is really at fault.