Now, let’s look at how to fix these issues step by step. If none of the above fixes work, the problem may be caused by deeper corruption or How to fix Office 365 login errors server-side issues. In that case, it’s best to contact Microsoft Support or your IT administrator. If disabling the antivirus resolves the issue, consider using built-in Windows Defender as it is less likely to cause conflicts. Your trusted tech help & troubleshooting hub. If the error occurs during a Windows update, the Windows Troubleshooter can help identify and fix the problem.