How to Fix Office 365 Login Error TAG: 4usqa

If you are using any of Microsoft's Office software, including Outlook, and are getting the "Something went wrong Login Error TAG: 4usqa" there's probably some kind of authorisation error preventing you from being validated correctly. Thankfully there are quite a few different troubleshooting steps you can take to solve this issue. These steps will work for Outlook, Office and all other tools included in Office 365 on Windows.

How to Fix Office 365 Login Error TAG: 4usqa

The error is frequently linked to a disruption in the authorisation components that Outlook depends on to validate user access. When any required identity or protection service fails to respond, Outlook cannot complete the sign-in handshake and the TAG: 4usqa error appears. Before you start anything, confirm that the affected user/s have the correct Microsoft 365 license assigned. Missing information protection or security components can disrupt authorisation.

Re-Enable the Application

• Open a web browser and sign in to the Microsoft Entra Admin Center using a Global Administrator account.
• Go to Applications and then to Enterprise Applications.
• Select Add filters and choose Application ID. Remove any other filters if necessary.
• Enter the following Application ID and apply the filter:

• Open the application and select Properties.
• Locate the setting titled Enabled for users to sign in and change it to Yes.
• Save the modification.
• Attempt to sign in again.

Clearing Cached Credentials

If Outlook continues to use cached authentication tokens:

• Sign out of the account inside Outlook and add it again.
• Optionally open Windows Credential Manager and remove any stored Microsoft Office or Outlook related credentials.
• Restart Outlook and attempt sign-in once more.

If the Application Was Already Enabled

If the setting was already set to Yes, the cause may lie elsewhere in your Microsoft 365 configuration. The following areas should be reviewed with an administrator.

Conditional Access Policies: A policy could block the application or the sign-in attempt for specific groups, device states, networks, or risk conditions.

Authentication Tokens or Device Registration: Tokens may be expired or corrupted. Consider forcing a remote sign-out and re-registering or re-adding the account profile on the device.

Automated Configuration Changes: Security baselines, scripts, or provisioning tools may have altered app permissions or disabled related components. Review any recent configuration changes within Entra ID.

Save the Logs and Get in Touch with Microsoft

If the above steps do not resolve the problem, collect sign-in logs from Microsoft Entra under Monitoring, filtering for the TAG: 4usqa event. The error codes and failure reasons in these logs will help your identity team or Microsoft support diagnose the remaining issue.