A reader reported a problem after installing a Cumulative Update (CU) on an Exchange 2016 server. It was no longer possible to access OWA and ECP after the installation. Both applications only returned a server error.
When calling up OWA, the error message read something like this:
Die Datei oder Assembly „Microsoft.Exchange.Common, Version=15.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35″ oder eine Abhängigkeit davon wurde nicht gefunden. Das System kann die angegebene Datei nicht finden.“ und OWA “
:-( Something didn't work out.
Your request could not be completed. HTTP status code: 500.
X-ClientId: 69461D0170F742F09942BB1B8E75C0C6
request-id 1a567512-c2b4-4d4e-8f05-5481c5713adf
X-OWA-Error System.Web.HttpUnhandledException
X-OWA version 15.1.1531.7
X-FEServer server name
X-BEServer server name
Date:12.10.2018 14:56:03
InnerException: System.IO.DirectoryNotFoundException“.
Similar error pattern when calling up ECP:
The important message here at this point:
Exception details: System.IO.FileNotFoundException: Die Datei oder Assembly „Microsoft.Exchange.Common, Version=15.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35“ oder eine Abhängigkeit davon wurde nicht gefunden. Das System kann die angegebene Datei nicht finden.
The functionality of OWA could be restored quite quickly using the "UpdateCas.ps1" script supplied by Exchange. The script can be started as follows using the Exchange Management Shell:
cd $exinstall cd .\Scripts\ UpdateCas.ps1
OWA could then be opened again without any problems, but still returned the error mentioned above. The cause was incorrect path information in the application settings for the ECP directory of the Exchange backend website. In this case, paths with a non-existent variable were specified for the "BinSearchFolders" key.
As can be seen in the following screenshot, the "BinSearchFolders" key does not contain absolute paths, but paths with the variable ExchangeInstallDir (%ExchangeInstallDir%):
However, the ExchangeInstallDir variable does not exist, hence the error message System.IO.FileNotFoundException. For ECP to work again, the corresponding paths for "BinSearchFolders" must be specified:
The correct paths can be determined with the Exchange Management Shell. The following command can be used for this purpose:
$folders = "$exinstall" + "bin;" + "$exinstall" + "bin\CmdletExtensionAgents;" + "$exinstall" +"ClientAccess\Owa\bin" $folders
The value must now be entered as described above. Then restart the IIS once using IISRESET.
As already mentioned, the ExchangeInstallDir variable does not exist, something may have gone wrong here during the update. For comparison, I checked other Exchange 2016 servers, in all installations the absolute paths were specified without variables. However, there is the ExchangeInstallPath variable, which could also be used here:
If OWA or ECP still do not work after these steps, it often helps to recreate the corresponding directories. The procedure is described here: