Software⏱️ 3 min read📅 2026-05-26

How to Fix: Firefox and Thunderbird keep crashing after updating to MacOS Tahoe 26.5

Firefox and Thunderbird crashing after MacOS update, frequent crashes every 15 minutes.


Firefox and Thunderbird keep crashing after updating to MacOS Tahoe 26.5 due to a known issue where the WebKit engine is not compatible with the latest version of the browsers. This incompatibility causes crashes every 15 minutes or so, resulting in frequent failures.

⚠️ Common Causes

  • Outdated WebKit engine compatibility
  • Insufficient system resources (RAM or CPU)
  • Conflicting browser extensions

🛠️ Step-by-Step Verified Fixes

Method 1: Update to Latest Firefox and Thunderbird Versions

  1. Step 1: Open Firefox and Thunderbird, and click on the three dots in the top right corner of each window.
  2. Step 2: Select 'Help' > 'About' to check for updates.
  3. Step 3: Install any available updates and restart both browsers.

Method 2: Disable Conflicting Browser Extensions

  1. Step 1: Open Firefox and go to the 'Add-ons' page.
  2. Step 2: Disable any recently installed or suspicious extensions.
  3. Step 3: Restart Firefox and try using Thunderbird again.

Method 3: Increase System Resources

  1. Step 1: Open the Activity Monitor in MacOS.
  2. Step 2: Find and select both Firefox and Thunderbird processes.
  3. Step 3: Increase the 'Memory' and 'CPU' allocations for each process to at least 512 MB and 10% respectively.

💡 Conclusion

By following these steps, you should be able to resolve the crashing issue with Firefox and Thunderbird on MacOS Tahoe 26.5.

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