Yes this is the same problem many people are seeing since 1 May 2026. Microsoft pushed an update on the authentication library used by the Office add-in and after that the token is not kept anymore between Excel sessions. So every time Excel opens, a new sign in is asked. MFA does not always show because the device is still trusted, but the prompt itself comes up.
There is an open ticket from Microsoft about it, https://admin.powerplatform.microsoft.com/support/knownissues/6355973, the issue is recognised on their side.
The workaround that solves it for most users is to close Excel fully, then delete what is inside the folder %LOCALAPPDATA%\Microsoft\Office\16.0\Wef. Some cases need also the folder %LOCALAPPDATA%\Microsoft\IdentityCache to be emptied. After this, the sign in stops appearing every time.
If the issue still continues, the next step is to remove the Microsoft Dynamics Office Add-in from Excel, Insert, My Add-ins, Manage, Remove, and install it again from AppSource. This forces a clean token.
For now no permanent fix from Microsoft, only the cache clean works as workaround until they patch it.
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Regards
Gregory Mavrogeorgis
