CommandBar not visible on modern ui lists and libraries

[ateusch]

Hi! Since the last security update for Sharepoint Server 2019 there is an issue with all lists and libraries in every site collection: The commandbar on top of lists and libraries is empty (no button is shown). In SharePoint classic ui everything works fine. After the update the problem occurs both on productive and test SharePoint.

Maybe this is because of the following error message: In the developer console of the browser there is the following exception for the api-call ‘/_api/SP.Directory.DirectorySession/User(principalName='…')?$select=sharePointLibrariesFirstRun,sharePointFiltersPaneFirstRun’ :

'Microsoft.Office.Server.Directory.FederatedDirectoryNotConfiguredException: Could not load file or assembly 'C:\ProgramData\microsoft\office\server\directory\client.config' or one of its dependencies. The system cannot find the file specified.

Any idea how to solve this issue in SharePoint 2019 on premise scenario?

[#2]

we have the some experiencing @ateusch 

I think we need to rollback. 

when I installed the update for the first time, the issue occurred. then it seems recovered when I run psconfiggui to update the database; but after finished the update on all server, the issue persist.

I can't find any way for workaround for now

trying to recover  

[#3]

update:
English user looks fine except the default TeamSite homepage(quick menu on the right hand just disappeared )
there's nothing to do with the error you put here. I checked all the event logs. only performance counter related error there.
anyway, I gave up here.

[#4]

@HardieYe You're right! In english site collection the command bar is working fine. In german site collection it is still not visible. I haven't found any hints for the error in log files either  :(

In my first post I mentioned that I get a "FederatedDirectoryNotConfiguredException" in browser log. I think this has nothing to do with the missing command bar, since this exception also appears in english site collection, where the command bar is visible.

Who else has problems with the command bar?  

[#5]

@ateusch Update: Microsoft is currently investigating this issue: 
https://support.microsoft.com/en-us/help/4484505/security-update-for-sharepoint-server-2019-sept-8-2... 

[#6]

@ateusch 

I have same problem after applying KB4484505.

As workaround you can:

1. Add English language to web if not already enabled and set preferred language in browser to English.
2. Disable modern view on site/web or on individual list/library until patch will be available https://techcommunity.microsoft.com/t5/microsoft-sharepoint-blog/how-to-disable-the-modern-experienc...

[#7]

@SlawekM 

Microsoft released the update to resolve the problem

https://support.microsoft.com/en-us/help/4461512/september-21-2020-update-for-sharepoint-server-2019...