
D365 F&O Open in Excel Issue - Not Signed In Automaticaly anymore
Hi there,
New IT Support at a firm here, I've recently encountered an issue from my Accounting team regarding a sudden change in their daily usage of Dynamics + Excel.
They state that before they could've just open a file from D365 in Excel and the addin would automatically sign them and let them work directly with no additional action needed, now they reported they all need to manually click the Sign In button everytime they open an Excel in desktop from the browser D365 page.
I know it's silly and probably you think "can't you just let them know to click the "Sign in" button and leave it as an "new update from MS" thing ? " -- unfortunately no, it came straight from the CFO as a VIP ticket and I've looked into it for a while now but I'm stuck.
Funny how the user who rose the ticket started asking Claude about it and wrote the sollutions from Claude in the ticket (already tried 3 / 4, but for 1 and 2 I need to raise it to L3 engineers)
Leaving the statement here in case it helps.
Thanks for help if this even is worth looking into.
Ticket
"I have an issue with D365 F&O usage of open in excel add-in. Normally, when I use this functionality in F&O an excel file is downloaded and when I open it, I was signed in automatically.
Starting with yesterday, when opening the excel generated by the system we had this error . We solved it by sing out and sign it again. Then, each time we have to sign in for each use - this is time consuming.
Searched info on this issue and found this:
1. Conditional Access change (most likely culprit)
Microsoft improved how Conditional Access policies are enforced in Microsoft Entra ID starting March 27, 2026. This change addresses a security loophole in which policies targeting all resources with specific exclusions could be bypassed in certain authentication scenarios
2. Office SSO no longer works silently
The "Require approved client app" Conditional Access grant is deprecated and causes errors with NAA (Nested App Authentication) token requests. An admin must completely remove this policy and switch over to the "application protection policy" grant.
3.Add-in version — check whether the Microsoft Dynamics Office Add-in in Excel was auto-updated (Insert → Add-ins → Manage). A recent update may have changed the authentication
4. Credential Manager (Control Panel → Credential Manager → Windows Credentials) — if there are expired or corrupted tokens for D365/Office, deleting them forces a clean re-authentication