Missing dll for workflow

Question

When attempting to access http://[domain]/sites/Home/_layouts/wrkmng.aspx I receive an error about a dll missing from the asp.net framework folder. I navigate to the folder and the dll is in fact NOT there.

The missing dll is: App_Web_wrkmng.aspx2a428413.44q7ajjl.dll.

I got this error when accessing "Workflows" from the Site Collection Site Settings (the Workflow Settings link right below "Workflows" works just fine). I believe I have been to this page before so I don't think it's been this way the whole time.

1. What would cause a dll to disappear?

2. Are the numbers in the file name linked to my instance of SP? As in, I can't just go download an App_Web_wrkmng.aspx.xxx.xxx.dll file right?

Answer 1

There was a security KB patch that caused the issue. Had an admin track it down, remove it, and it's worked ever since. I believe it was the November 2018 Security and Quality Rollup patch