We have recently experienced a strange problem (starting at the end of december 2020) where our customer site (Episerver ver. 11.9.1), hosted by Episerver, suddenly stops serving static images, for example the static logo we use in the header.
Other than the missing static images the site appears to be working, albeit slow. Then the site begins to slow down and eventually stops responding and doesn't restart when hacking the web.config file. In this state the site doesn't respond to anything we do, and Episerver support needs to go in and restart the site for us.
The logs and the event log doesn't show anything out of the ordinary, on the contrary, it doesn't show anything at all.
This has happened on two occations, roughly one month apart and can't seem to be locally reproduceable.
Have anybody seen/experienced something like this before?
We have disabled all scheduled jobs and have no "out of the ordinary" InitializableModules.
Any insights is helpful
When you say the site is hosted by Episerver, is that in the DXP service or is it an old-school Everweb setup? If you're on DXP you should have access to Application Insights via Azure portal which is usually a good starting point when trying to track down the root cause of issues like this. Things to look at would be error rate, CPU usage and Memory usage and whether any changes in those correspond with an increase in traffic levels either to the site in general or to specific pages.
Given the timings, I'd wonder whether it might be triggered by a crawler of some kind? It would be worth taking a look through the logs to see whether there are any unusual user agents which are only cropping up at the times of the incidents.
Hi Paul, thanks for replying!
Unfortunately we are currently running on Everweb, so access to Application Insights via Azure Portal isn't available to us.
The crawler scenario is a interesting one and worth looking into further. Unfortunately the logs where either dialed down at the time of the incidents or they didn't write anything at all, so they aren't very helpful.