A custom mobile Outlook add-in is not loading, which is working well in the Outlook Web

1. Basic troubleshooting steps
Validate the plugin manifest
xml
<! -- Check for MobileFormFactor support in manifest -->
<Requirements>
  <Sets>
    <Set Name=“Mailbox” MinVersion=“1.1”/>
  </Sets>
</Sets> </Requirements>
<MobileFormFactor
  <ExtensionPoint xsi:type=“MobileMessageReadCommandSurface”>
    <! -- Must contain mobile configuration -->
  </ExtensionPoint>
</MobileFormFactor>
Running HTML
2. Clear client-side cache
Android:
bash
adb shell pm clear com.microsoft.office.outlook
iOS:
Uninstall and reinstall Outlook
Disable “Battery Optimization” on first boot
3. Permission and Deployment Check
Verify API permissions
 Verify the API permissions.
# Check Azure AD application registration permissions
Get-AzureADServicePrincipal -Filter “AppId eq ‘YOUR_APP_ID’” | 
Select -ExpandProperty Oauth2Permissions
Required permissions: Mail.ReadWrite, MailboxSettings.Read
4. Redeploy the plugin
powershell
# Manage via Exchange Online
Publish-OutlookAddIn -ManifestFile “manifest.xml” -OrganizationAddIn
5. mobile-specific fixes
 Force HTTPS loading
Ensure all resource URLs use https://
Disable mixed content:
html
<meta http-equiv=“Content-Security-Policy” content=“upgrade-insecure-requests”>
Run HTML
6. Network Policy Adjustment
powershell
# Enterprise environments need to allow plugin domains
New-MobileDeviceMailboxPolicy -Name “AllowAddInDomains” -AllowedInboundUrlPatterns @(“*.yourdomain.com”, “*.azurewebsites.net”)
7. Debugging and log collection
 Android debugging
bash
# View Outlook mobile logs
adb logcat -s Outlook | grep “AddInLoader”
 iOS Diagnostics
8. Search through the Xcode device console:
[OutlookAddIn] Error Domain
9. Simulator test
bash
# Test in Android emulator
emulator -avd Pixel_API_30 -http-proxy http://localhost:8080
10. Proxy Capture
Configure Charles Proxy
Capturing outlookmobile://addin protocol requests