This article applies to Microsoft Office Add-ins:
- Messageware SERT
- Messageware Mail Forms
- Messageware Message Save
SUMMARY
When the certificate that is being used for the Office Add-in website expires, the Add-in is unable to start.
SYMPTOM
Sometimes when trying to launch an Office Add-in the application will not start and the following message appears: "Something went wrong and couldn't load this app. Please try again later".
Messageware Add-ins (Outlook Add-ins/Office Add-ins) run under the Default website in IIS. The Microsoft architecture for Add-ins blocks access when the certificate is expired. The Add-in framework does not trust the website and will not load the app.
RESOLUTION
To resolve this behavior replace the expired certificate with a valid one on the server where the Outlook Add-in is running following the instructions below.
Step 1: Import a Valid Certificate:
- Copy a valid certificate to a temp folder on the server where the Outlook Add-in is running from
- Double click on certificate to import it and select the 'Local Machine' or 'Store Location'
- Enter the path to the valid certificate and enter the password for the 'private key' when prompted
- Choose 'Automatically select the certificate store based on the type of certificate' and select Next
- Click 'Finish' to complete the import
Step 2: Update the web site certificate in IIS:
- Launch the IIS Manager and navigate to the Default Web Site
- Click Bindings on the right pane, under 'Actions'
- Click on 'https' and click the drop down under 'SSL Certificate'
- Choose the valid certificate and click OK