Why is a "Failure - refresh_token is invalid" window appearing?

If the following Failure - Refresh_token is invalid window appears when you launch Easy MTD or after you click the Go button, the refresh token that was applied to Easy MTD when it was connected with HMRC is no longer valid. Refresh tokens naturally expire after a certain number of days (this is a HMRC policy).

To stop the error from occurring, the process of connecting Easy MTD with HMRC will need to be performed again. Start this process by clicking the Connect button for the applicable business on the Businesses page in Easy MTD.

More: For further details about connecting Easy MTD with HMRC, refer to the Connecting with HMRC section of the help.