We are running on PRPC 7.1.7 with Pega CS 7.1 in a multi node environment. We started seeing distorted UI presented after login to application. Same time we can see (ticcontent.StaticContentClient) ERROR - 404 on request: Errors in PegRules Logs. We compared the CSS files with the properly loaded screen and found that some of the CSS files are not loaded during that time.
Server restart with cache clear resolved this issue but we cannot face this again in Production environment.
In addition, DeleteUnusedCSSFiles and DeleteUnusedStaticContentFiles agents are stopped in those nodes faced the issue. Enabling those agent will solve the problem?
There is a BUG in 7.1.7 code which is fixed via HFIX-22715 to correct the Activity "PZDELETEORPHANSTATICCONTENT" such that it does not delete CSS files needed by the Designer Studio. Also, entire DB cache clear is not required when you see distorted UI issues, one table will do for 7.1.7 versions. (Mentioned in the below link).
However, when you are sure that the above agents are disabled permanently the BUG might not create the issue. The reported problem is indeed an issue when the above agents are running, it doesn't mean that we need to turn off the agents where it can lead to some other issues as stale static content remains on the system.
This issue created a problem for the designer studio's where the requires CSS styles were removed and may not be a problem for production end-user portals, but being well aware of the issues & background can help us to avoid this problem in production.