Hello,
I had to back-peddle on an xwiki upgrade because the left navigation menu disappeared after the upgrade. Now I did read about a similar issue where what fixed it was clearing his browser cache (this was in 2017)…fair enough but this xwiki is in use by about 200+ people now using IE, Chrome, and Firefox. Has anyone come across a quick way to resolve this for everyone at once?
Yes there’s a way! 
Simply upgrade to a more recent version (I don’t know your version since you didn’t mention it but my guess is that it’s oldish) since it’s fixed there I recommend the LTS one, i.e. 10.11.8.
We are using XWiki 10.11.3 Ubuntu in docker
This issue is not yet fixed in XWiki 10.11.x LTS. So you still have to require all your users to delete the browser cache after each maintenance upgrade, or upgrade to a more recent non-LTS release (not sure which release is actually supposed to resolve the upgrade issue, IIRC it’s some 11.x version).
Addendum: This issue was tracked in Loading... and Loading..., and is supposed to be resolved with the latter (the first meanwhile being marked as a duplicate). It’s fixed from XWiki 11.1 on and I especially asked there if the fix could be backported to the then-new LTS release, which unfortunately according to @surli is not possible as the fix is too intrusive and might introduce regressions.
See Loading...
@vmassol: The current 10.11 LTS branch is still relatively new, what’s an LTS branch’s usual lifetime, so can you roughly estimate when we can expect a new LTS version which includes this fix?
ok my bad then, I thought it had been merged on the 10.x branch.
The 10.11 LTS branch is 6 month old and an LTS stays for 1 year after which a new LTS emerges.
See https://dev.xwiki.org/xwiki/bin/view/Community/VersioningAndReleasePractices for more details.
Don’t know, we only backport major bugs that are not risky on the LTS branch.
Note that 11.3.x is quite stable and I recommend trying it.
Ah, thanks for the link! That was the information I was lacking.
Well, basically in about 6 month then, I guess.
That’s a sufficient answer for me, I’ve only 7 users and meanwhile they know what to do if XWiki is upgraded.
I’d rather wait for a new LTS release then, but @bdub probably should think about upgrading with 200 users…
I appreciate all the info guys. I will review this week and let you know what I come up with.