This one has been driving me crazy and I've posted a couple places about it, but not here. I'm 99% sure this is not a CF problem per se, but something with isapi_redirect, IIS, Tomcat and maybe web.config. Windows 2016 server, IIS 10 and Adobe ColdFusion 2018 using Tomcat. The server has about 8 sites on it and one site is getting intermittent 500 errors. All other sites remain up and responsive. Failed Request Tracing shows "Filter Error - Incorrect Function 0x1" The site will come back up if you recycle the app pool for that site, or restart that site in IIS. I have the app pool set to recycle every 10 minutes for now to minimize downtime (which is now at about 4-6 times per day - could be mid day when presumed traffic is heaver than middle of the night - it doesn't seem to matter). In March it was doing it frequently (once per day or more) and we recreated the site - new web root, new IIS config etc. same thing. I then noticed that the uptime on the server was several weeks, where normally it should reboot on every Sunday night and also pop a notification that updates were installed and a reboot is needed (neither of those happy anymore). Did the reboot and the site was fine - until 6/22. Then the 500s started again. I've scoured every log and there is no single event, template, or URL that I can see that causes it. Charlie has spent a bit of time working with us on this but we're still experiencing the errors. One thing I had done back in March was strip the web.config of the redirects - other than http to https - not sure if it was that or the reboot that gave us a few months respite. Tomorrow in desperation I'll clone the site into a new directory, create a new IIS site and run wsconfig on it to see if that helps. Every time I now Google for this error I'm only getting my posts about it so for some reason I seem to be complete alone in this quagmire!

bit of a shot in the dark but you might try the boncode connector in place of the ISAPI stuff. we found it much easier to manage + more performant back when we ran ACF + IIS. If you have a lot of other sites it's maybe not convenient to experiment just to solve a problem with one, tho

I think there are 8 production running sites on there, so probably more than I want to do on a whim. It was just down twice though in 30 minutes though.

I'll say, more generally, that of the major architectural changes I've made in the 20 years I've been running CF servers, going from isapi to boncode was a big relief, and then going from IIS to nginx + docker was an even bigger relief in terms of 'time spent dealing with devops issues'

what's super frustrating is when it happened two years ago I found a reference in an email to charlie "now that I fixed that permissions error" - but no other reference to it anywhere. I'm not even sure if that was related to that sites 500s or not.

Yuck, super frustrating. Long shot, but maybe try clearing the template cache. We've seen a site suddenly start throwing nonsense errors, fixed by that cache clear. Luckily it's not common, but has happened, more than once. In our case though, once that starts, there are a lot of errors until the cache clear, so it doesn't sound like the same pattern.

well just tried that and got 500s within the hour - thanks though!

It seems it's rewrite rules in web.config - specifically ones that are doing SEO stuff 😐