CultureNotFoundException when selecting an LCID 4096 language in OWA for Exchange Server 2016

Applies to: Exchange Server 2016 Enterprise EditionExchange Server 2016 Standard Edition


Consider the following scenario:
  • Microsoft Exchange Server 2016 Cumulative Update 7 (CU7) is installed on a computer that's running Windows Server 2016.
  • A user signs in Outlook on the web (Outlook Web App) and tries to change the language through:
    OWA > Options > General > Region and time zone settings.
  • The user selects the language that has an LCID value of 4096, for example, English Belgium.

In this scenario, the user receives a "something went wrong" error message and OWA crashes. This issue prevents the user signing in until the administrator changes the language setting back to a supported one. In addition, you may find the following event logs are recorded:

Exception type: System.Globalization.CultureNotFound
Exception Exception message: Culture isn't supported. Parameter name: culture 4096 (0x1000) is an invalid culture identifier.


This issue occurs because the newly-added cultures don't have valid LCIDs.


For Exchange Server 2016, install Cumulative Update 9 or a later cumulative update for Exchange Server 2016.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


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