When starting the modern Office add-in, it immediately fails with error "Access is denied".

The issue can be a result of different reasons, e.g. a cookie/ad blocker or a corrupt IE localStorage that is necessary to run our add-in. Should only happen on Outlook for Windows or Outlook for Web when using Internet Explorer.

For advanced users, a lot of background information to the issue can be found here:


There might be different reasons for the issue, so please try the following steps one by one and check if it is working again

Solution: Check for active ad blocker

If the issue is occurring in your browser, make sure you don’t have any ad blocker enabled which might interfere with the add-in. If you have one, please turn it off, at least temporarily, to check if the add-in is working again.

Solution: Clear Registry Cache

  • Close Outlook

  • Open Windows registry with tool regedit (Help)

  • Open the following tree path:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\Cache\
  • Delete the whole key "Extensible Cache" including all subkeys

  • Repeat the same with the LowCache folder:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\LowCache\
  • Delete the whole key "Extensible Cache" including all subkeys here too

  • Restart Outlook and check if it is working

Solution: set integrity level

  • Close Outlook

  • Open a command line - cmd (make sure to not run as administrator)

  • Run the following command to set the integrity level for the AppData/LocalLow correctly to "Low"

icacls %userprofile%\Appdata\LocalLow /t /setintegritylevel (OI)(CI)L
  • Restart Outlook and check if it works.