Assuming you do NOT have UTeamFix locally installed on your playing computer...
Solution a: in between servers, exit the game and restart.
Solution b: bind a keybind to "open entry" and another to "obj garbage". When swapping servers, first hit "open entry", then "obj garbage" bind, then join.
THIS IS NO COMPLAINT ABOUT UTEAMFIX!
This problem was not created by me, it has been there all the time and won't be solved (except as stated above). If you would play more custom maps or even some mods you would get this "error" much more often with countless other files...
-=]I AM GETTING TOO OLD FOR SUBTLETY[=-
mail: chaos.worx[at]gmx.net
IRC Quakenet +OTR: }TCP{Wolf @#oldunreal @#tcp.clan
Jabber/XMPP +OTR: Wolfy359@jabber.org
Threema: CR6Y9YSS
Signal: see profile
ICQ: dead since russian takeover disables OTR
@Xavious: that doesn't delete files from CACHE folder, but clears from memory loaded unused files, so they can be loaded again from CACHE folder in different versions if needed.
I have such bind: