Recent Bugs in Classic Outlook Demand Attention
Microsoft has recently tackled a significant issue affecting both Classic Outlook and Word, where users experienced excessive CPU usage—spiking as high as 50% during typing activities. This glitch has raised considerable concerns among users relying on Classic Outlook.
In yet another setback for the Classic Outlook application, Microsoft confirmed the presence of sign-in difficulties tied to specific error codes: CAA2000B, 4usqa, and 49dvs. This marks the third major concern within the past month as Microsoft accelerates its efforts to transition users to the New Outlook for Windows platform. Notably, last month witnessed complications with Classic Outlook downloads as well.
Details on the New Sign-In Issues
Regarding the ongoing sign-in problems shared by both Outlook for Windows and Outlook for Mac users, Microsoft issued the following statement:
Starting around May 7, 2025, some users that open Classic Outlook encounter sign-in errors including:
Additionally, users of Outlook for Mac are also affected, facing similar sign-in errors:
Error Message
Something went wrong.[49dvs]
Sign-in Error Details
We couldn’t sign you in. If this error persists, contact your system administrator and provide the error code CAA2000B.
AADSTS500014: The service principal for the resource is disabled.
Another Error Message
Something went wrong.[4usqa]
Investigations have revealed that a disabled service principal with the ID 40775b29-2688-46b6-a3b5-b256bd04df9f is at the heart of these issues. Reactivating this principal may resolve the sign-in difficulties.
Microsoft Offers Workaround Solutions
In response to these challenges, Microsoft has developed a comprehensive workaround to alleviate the sign-in issues. The tech giant noted:
The Outlook and Microsoft Information Protection Teams are actively investigating this issue. We will provide updates as more information becomes available. Users can track this issue on the M365 Service Health Dashboard, identified as EX1072812.
To help mitigate the sign-in issues, it is advised to enable users to log into the Microsoft Information Protection API as follows:
Log into the Entra portal at Microsoft Entra.
Search for Information Protection or use the ID 40775b29-2688-46b6-a3b5-b256bd04df9f, and select Microsoft Information Protection API from the results.
On the API page, ensure that Enabled for users to sign-in is set to Yes.
Click Save to finalize the changes.
For additional assistance, users can refer to the official support article detailing the sign-in errors here on Microsoft’s website.
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