Symptoms
After you install the Microsoft Exchange Server March 2024 security update (SU), the My Templates add-in in Outlook on the Web (OWA) can't be accessed.
When you try to start the My Templates add-in, you receive the following error message:
Add-in Error Something went wrong, and we couldn't start this add-in. Please try again later or contact your system administrator.
Resolution
To fix this issue, install the following update:
