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Repairing Corrupted Fonts and Font Book Problems

Issue Description 

Text appears distorted, apps crash when opening fonts, or Font Book reports errors. 

Common Causes 

  • Corrupt font files 
  • Duplicate fonts 
  • Third-party font managers 

Step-by-Step Solution 

Step 1: Validate Fonts 

  • Open Font Book 
  • Select All Fonts 
  • Click File → Validate Fonts 
  • Remove fonts marked with serious errors 

 

Step 2: Remove Duplicate Fonts 

  • In Font Book, click Duplicates 
  • Resolve duplicates automatically 

 

Step 3: Reset Font Cache 

  • Restart Mac in Safe Mode 
  • Safe Mode clears font caches automatically 

 

Step 4: Restart Normally and Test 

  • Launch affected apps and verify text rendering 

Explore Further 

  • Remove unused third-party fonts 

Prevention & Best Practices 

Install fonts only from trusted sources.