FIX: CAA90049 Sign-in error in Microsoft 365 apps.
This guide contains instructions to fix the sign-in error code CAA90049 in Office 365 apps (Entra ID Sign-in error code: 9002341).
Issue: When a user tries to log in to any Microsoft 365 application, such as Word, Excel, Outlook, Teams, or OneDrive, the login fails with error code CAA90049 (Session key is empty) and Entra sign-in logs show "Sign-in error code 9002341" with "Failure reason: User is required to permit SSO".
Cause: The error is commonly caused after installing a Windows or Office update, or due to corrupted authentication tokens or cached credentials.
Error message:
Something went wrong
We couldn't sign you in. If this error persists, contact your system administrators and provide the error code CAA90049.
Addition problem information:
Error code: CAA90049
Correlation ID: 741ab*****4606
Server message: Session key is empty
How to FIX the Sign-in Error code CAA90049 in Microsoft 365 apps. (Entra ID Sign-in Error Code 9002341).
Method 1. Login to Microsoft 365 on the Web.
An easy method that sometimes resolves the CAA90049 sign-in error in Microsoft 365 apps is to sign in to your Microsoft account using the EDGE browser.
1. Open EDGE browser and navigate to Microsoft 365 login page.
2. Sign in with your MS account credentials and, once logged in, open any Office application and see if the problem persists.
Method 2. Remove & Re-add Microsoft Account in Settings.
The second method to fix the sign-in error CAA90049 in O365 apps, is to disconnect the MS account in Windows "Accounts" settings and re-add it.
1. Go to Start > Settings > Accounts > Access work or school.
2. Select the Microsoft account and click Disconnect.
3. When done, do one of the following:
-
- Click the Connect button on the "Access work or school" screen to connect your MS account again and re-register the device.
- Open any Microsoft 365 app, follow the prompts to sign-in to your Microsoft account, but at the final screen, UNCHECK the option "Let my organization manage my device" and click OK.
Method 3. Remove cached Microsoft account information and credentials.
One of the most efficient methods to solve the login error CAA90049, in Office 365 apps, is to delete all folders in the following locations to clear the cached credentials.
- %localappdata%/Microsoft/OneAuth
- %localappdata%/Microsoft/IdentityCache
To navigate to these locations and clear the cached O365 credentials:
1. Press the Windows + R keys to to open the "Run" command box.
2. Type the following command and press Enter:
- %localappdata%/Microsoft/OneAuth
3. Press CTRL + A to select all files and press the Delete button to remove them.
4. Now, press the Windows + R keys again, type this command and press Enter:
- %localappdata%/Microsoft/IdentityCache
5. Press CTRL + A to select all files and press the Delete button to remove them.
6. Now restart your PC and open any Microsoft 365 app to check if the problem persists.
Method 4. Re-Register the Device in Microsoft Entra.
The next method to fix the CAA90049 sign-in error in Microsoft 365 apps, is to register the device in Microsoft Entra:
Step 1. Verify that Device is Enabled in Entra Admin center.
1. Navigate to Microsoft Entra Admin center > Identity > All Devices.
2. Select the device name of the user who can't sign in to Microsoft apps due to error CAA90049 and ensure that is not disabled.
Step 2. Re-register Device with Microsoft Entra.
1. Open the Command prompt as administrator.
2. In command prompt give the following command to register the device in Entra:
- dsregcmd /forcerecovery
3.
Click "Sign in" in the dialog and Sign-in with your Microsoft account credentials.
4. Restart the computer, or sign out and sign back in on the device to complete the recovery.
5. Open any Microsoft 365 app and check if the problem persists.
Method 5. Sign-out the User from all sessions in Office 365 Admin center.
1. Navigate to Microsoft 365 admin center > Users > Active Users.
2. Click on the user who is having trouble logging in due to error "CAA90049" and in Account tab choose Sign out of all sessions.
3. Restart the user's device, and then sign back in to any Microsoft 365 app to check if the issue is resolved.
Method 5. Uninstall & Reinstall Office apps.
The final method to fix the mentioned error is to remove and reinstall Microsoft Office apps.
1. Close all Office programs.
2. Visit Microsoft 365 troubleshooters page, expand Microsoft 365 uninstall troubleshooter and click the Start button.
3. Then choose Open on the message says "This site is trying to open Get Help".
4. Then click Yes to uninstall Microsoft 365 or Office.
5. When the uninstall is complete, restart your computer.
6. Finally, proceed to install Microsoft Office again.
That's it! Which method worked for you?
Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.
Frequently Asked Questions
What is error code CAA90049 in Office 365 apps?
Error code CAA90049 occurs when a user attempts to sign in to Microsoft 365 applications like Word, Excel, Outlook, Teams, or OneDrive. This error indicates that the session key is empty, often after a Windows or Office update or due to corrupted tokens or cached credentials.
How can I resolve the CAA90049 error via the web?
To resolve the CAA90049 error via the web, log in to your Microsoft account using the EDGE browser. Navigate to the Microsoft 365 login page, sign in with your credentials, and open any Office application to see if the issue has been resolved.
What steps should be taken if removing and re-adding a Microsoft account doesn't fix the error?
If removing and re-adding a Microsoft account doesn't resolve the error, you can try clearing the cached credentials by deleting folders in %localappdata%/Microsoft/OneAuth and %localappdata%/Microsoft/IdentityCache. Additionally, you may need to ensure your device is registered correctly in Microsoft Entra.
How can I re-register a device in Microsoft Entra to fix the error?
To re-register a device in Microsoft Entra, verify that the device is enabled in the Entra Admin center. Then, open the Command prompt as an administrator, execute the command 'dsregcmd /forcerecovery', sign in with your Microsoft account credentials, and restart the device or sign out and back in to complete the recovery.
