Hi @Alex Vieira ,
Thanks for the response.
May I know if you have also applied the latest security update(KB5000871) after upgrading to CU19? If yes, how did you install the patch?
Considering that as stated in the known issues section in the link earlier, OWA or ECP might stop working if the SU is installed by directly double-clicking it, so if that is your case, it's recommended to try reinstalling the SU using elevated permissions and see the result.
If issue persists, please check the IIS Settings for ECP Virtual Directories Path using the steps below:
1.Start IIS Manager on the server. Navigate to Exchange Backend website > ECP Virtual directory, select Application settings > BinsearchFolder.
2.If the directory paths resemble the following:
%ExchangeInstallDir%bin;%ExchangeInstallDir%bin\CmdletExtensionAgents;%ExchangeInstallDir%ClientAccess\Owa\bin
Please replace them with the paths below and then restart IIS to check the result:
Note: The paths must point to where Exchange Server is installed. The following examples assume that the program is installed on drive C. If it is installed on a different drive on your server,then you would need to use the path that's appropriate for your installation.
C:\Program Files\Microsoft\Exchange Server\V15\bin;C:\Program Files\Microsoft\Exchange Server\V15\bin\CmdletExtensionAgents;C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa\bin
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