How to fix Microsoft Office Add-in error issue when logging in to my 365?

Hi @Vincent Louh

Before you spend more hours on this, there's something you should know. There is an active, widely reported problem with Office store add-ins right now. It's tracked on the Office dev GitHub as a regression, with an add-in developer reporting 50+ customer reports of the same failure starting just days ago, and the error is word for word yours: "Error loading add-ins. One or more add-ins failed to load. See your add-ins." Some people also get a "you don't have permission to use this add-in" variant. So the timing of your issue is probably not a coincidence, and your machine may be fine.

Your symptom actually fits that picture well. Store add-ins are checked against your account when you're signed in, and that check is what seems to be breaking. Signed out, that account check doesn't happen the same way, which is why everything magically works.

That said, there's one local setting worth checking first, because it's tied to your account exactly like your symptom is. Open Word, go to File > Account > Account Privacy > Manage Settings, and make sure "Turn on optional connected experiences" is enabled. Store add-ins are part of those optional connected experiences, so if this is off for your account, add-ins fail precisely when you sign in. Turn it on, restart all Office apps, and try again.

If that was already on, do two more quick things. Open Windows Credential Manager (search it from Start), go to Windows Credentials, and remove the stored entries starting with MicrosoftOffice16, then restart Word and sign in fresh, since a stale cached identity produces account-only failures like this. And if that changes nothing, run a repair from Settings > Apps > Microsoft 365 > Modify, Quick Repair first, Online Repair if needed.

If the privacy setting is on, credentials are clean and the repair doesn't help, then you're most likely just caught in the ongoing service-side issue, and no amount of local cleanup will fix that. In that case the honest answer is to wait for Microsoft's fix, and you can watch the GitHub issue below for updates. Since you're on Microsoft 365 Personal, you can also raise it with consumer support at https://support.microsoft.com/contactus so it's on record.

References: https://github.com/OfficeDev/office-js/issues/6952 https://learn.microsoft.com/en-us/microsoft-365-apps/privacy/optional-connected-experiences