After updating Firefox to the latest version, an error with the message "The procedure entry point js_SaveRegExpStatics could not be located in the dynamic link library js3250.dll" may appear when starting Firefox. This occurs when one or more Firefox files could not be changed while upgrading.

Conflict with ZoneAlarm Extreme Security software

ZoneAlarm Extreme Security may be the reason for this error.

If you have ZoneAlarm Extreme Security:

• Temporarily disable the ZoneAlarm Extreme Security by right-clicking on the Z icon in the system tray and selecting Shutdown ZoneAlarm Extreme Security. Then try to reinstall Firefox.
• In the Zone Alarm window, go to Browser Security > Settings > Advanced, and click "Clear Virtual Data". Then try to reinstall Firefox.

Please click to Submit additional feedback and tell us which solution worked best for you.

Clean installation

This error is fixed by erasing the Firefox program folder then re-installing Firefox.

1. Hold down the (Windows logo) key and press R. This will bring up the Run dialog.
2. In the Run window, type %PROGRAMFILES% and press OK.
3. Windows Explorer will open with a list of your programs. Find Mozilla Firefox in the list and right click it. Then, choose Delete.
   • If you receive an error when deleting the folder, Firefox may still be running in the background. Follow the steps below under Ending a running process to end the existing process.
4. Once the folder is deleted, re-install Firefox from the Firefox download page. For instructions, see Installing Firefox on Windows

Ending a running process

If you were unable to delete the Mozilla Firefox folder by following the steps above, Firefox may still be running in the background.

1. Hold down Ctrl and Shift, then press Esc. This will open the Task Manager.
2. At the top, click the Processes tab
   • Tip: if you don't see the Processes tab at the top, double click in the empty space at the top of Task Manager
3. In the list that opens, look for firefox.exe. If it is shown, it means that Firefox is still running in the background.
4. To force Firefox to quit, click firefox.exe in the list, then press End Process
5. Windows will ask you if you want to end the running process. Press Yes to force Firefox to quit.
6. Finish following the steps above in the Clean installation section.