How to Investigate Failed Microsoft 365 Sign-Ins

One of the most common tickets an administrator receives is deceptively simple:

“I can’t log in.”

That statement doesn’t tell us very much.

An authentication problem could involve:

  • Incorrect credentials
  • MFA
  • Conditional Access
  • Device compliance
  • Account status
  • Authentication methods
  • Application access
  • Risk-based controls

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