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Microsoft 365 has become the productivity backbone for organizations of all sizes, offering a suite of powerful tools like Outlook, Teams, SharePoint, OneDrive, and more. But with widespread adoption comes a steady flow of support tickets.

Whether you’re on an IT support team in an MSP or handling user issues solo as internal IT support, understanding common Microsoft 365 problems — and how to fix them — can save time and frustration. Let’s break down some of the most frequent support tickets and how to resolve them.

1. Password Resets and Account Lockouts

The Issue:

Users often forget passwords or get locked out due to multiple failed login attempts, triggering account lockouts or MFA (Multi-Factor Authentication) prompts.

How to Resolve:

• Reset via Microsoft 365 Admin Center:
  Go to Users > Active Users, select the user, and choose Reset Password.
• Unlock Account:
  You can manually unblock accounts under Azure AD > Users > Sign-in logs or advise users to wait the lockout duration.
• Enable Self-Service Password Reset (SSPR):
  Configure SSPR in Azure AD to allow users to reset passwords on their own, reducing ticket volume. (Keep in mind, SSPR has the potential to create additional issues for users by affecting their UX and creating other technical trouble such as sync issues with on-prem DC’s, etc.)

Pro Tip: Ensure users are registered for MFA with up-to-date recovery methods.

2. Outlook Not Syncing or Loading

The Issue:

Outlook can be a frequent pain point — whether it’s not syncing mailboxes, stuck on “Loading Profile,” or not opening at all.

How to Resolve:

• Check Internet Connection and M365 Service Health.
• Rebuild Outlook Profile:
  Use Control Panel > Mail > Show Profiles to create a new one.
• Clear Cached Credentials:
  Delete from Credential Manager > Windows Credentials > MicrosoftOfficeXX_Data.
• Use Microsoft Support and Recovery Assistant (SaRA):
  A diagnostic tool that can automatically detect and fix common issues.

3. Microsoft Teams Issues (Login Failures, Sync Errors, Calendar Not Showing)

The Issue:

Teams has many moving parts. Common complaints can include missing calendars, failed logins, or syncing problems with channels and messages.

How to Resolve:

• Clear Teams Cache:
  • Windows: C:\Users\<User>\AppData\Roaming\Microsoft\Teams
  • Mac: ~/Library/Application Support/Microsoft/Teams
• Check Licenses:
  Confirm the user has a Teams license assigned in the M365 Admin Center.
• Verify Exchange Online Mailbox:
  Teams relies on an Exchange mailbox to pull calendars. Missing mailbox = missing calendar.
• Run Teams Troubleshooter:
  The SaRA tool also includes Teams diagnostics.

Heads up: Teams updates frequently — ensure users have the latest version.

4. OneDrive Sync Problems

The Issue:

Users may see red “X” icons, syncing errors, or complaints that files aren’t updating.

How to Resolve:

• Reset OneDrive Client:
  Within the Run dialog box: %localappdata%\Microsoft\OneDrive\onedrive.exe /reset
• Check Storage Quotas:
  Ensure users haven’t exceeded their storage limits.
• Sign Out and Back In:
  Helps reinitialize the sync and resolve auth issues.
• Check File Path Lengths:
  Paths over 400 characters can break syncing.

Bonus Fix: Educate users on using the “Files On-Demand” feature to save local space.

5. License or Activation Errors in Office Apps

The Issue:

Users may encounter “Unlicensed Product” errors or constant sign-in prompts in Word, Excel, or other Office apps.

How to Resolve:

• Confirm License Assignment:
  Log into your M365 admin dashboard, within the users tab, find the user and confirm their assigned licenses
• Remove and Re-add Account:
  Go to File > Account > Sign Out, then sign back in with the correct licensed account.
• Clear Credentials in Credential Manager.
• Repair Office:
  Use Control Panel > Programs > Office > Change > Quick Repair.

6. Email Delivery Issues (Missing, Delayed, or Rejected Emails)

The Issue:

Users may complain about emails not arriving, delays, or bounce-back errors.

How to Resolve:

• Check Exchange Message Trace:
  • Use the Exchange Admin Center > Mail Flow > Message Trace to track messages.
• Check Spam or Quarantine:
  Visit security.microsoft.com > Email & Collaboration > Review > Quarantine.
• Review Mail Flow Rules (Transport Rules):
  Miss-configured rules can block or redirect emails.
• Check MX Records:
  Especially important after domain setup or migration.

7. SharePoint or OneDrive Permissions Issues

The Issue:

Users can’t access shared documents or receive access denied messages.

How to Resolve:

• Verify Permissions:
  In SharePoint or OneDrive, go to the file or folder, click Manage Access, and adjust accordingly.
• Check Group Memberships:
  Some access is controlled by M365 Groups or Teams. (Note: It’s a best practice to assign access via groups or security groups)
• Check External Sharing Settings:
  Admins can restrict guest access at both the site and tenant level.

Quick Fix: Reshare the file and double-check user email spelling.

8. MFA/Authentication Issues

The Issue:

Users can’t receive MFA codes, have changed their mobile device that had the authenticator installed, or are locked out of second-factor verification.

How to Resolve:

• Reset MFA for the User:
  In Azure AD > Users > Authentication Methods, clear existing methods.
• Temporarily Disable MFA:
  If allowed by policy, disable to let users in and reconfigure.
• Encourage Use of Authenticator App with Backup Codes.

Summary: Tips for Reducing M365 Support Tickets

• Train users on common self-service features.
• Leverage automation tools like Microsoft’s SaRA and SSPR. (When applicable)
• Monitor M365 Health via the Admin Center dashboard.
• Standardize configurations using Intune or GPOs where applicable.
• Stay up-to-date on Microsoft 365 Roadmaps and deprecation notices.