Find and copy your Profile :

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

then uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : (for the future do below since can not open Firefox)

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

An error message about XPCOM missing or about platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder. This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files. You can do a clean reinstall to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

• download the Firefox installer and save the file to the desktop
  *https://www.mozilla.org/en-US/firefox/all/

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

• do NOT remove "personal data" When you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

• it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling
• http://kb.mozillazine.org/Uninstalling_Firefox

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data When you uninstall and reinstall or update Firefox, but make sure NOT to remove personal data When you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then you can create a new profile to test if your current profile is causing the problem.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

tert said

Hi, I searched all over and was not able to find a solution to my problem. I can't access firefox at all. I keep getting this error messages: The procedure entry point?DllBlocklist_SetDllServices@@YAXPEAVDIIServicesBase@detail@mozilla@@@Zcould not be located in the dynamic link library C:\Program Files (x86)\Mozilla Firefox\xul.dll and Couldn’t load XPCOM I am hoping there is a way to fix it without losing everything. Thank you in advance for your time and assistance. T

Pkshadow said

Find and copy your Profile :

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

then uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : (for the future do below since can not open Firefox)

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Hi Pkshadow Thank you so much for the quick response to my problem, I will have to try this tomorrow. I did find my profile and will save it before continuing, is there anywhere I can look to see which version I have before reinstalling. Thank you again and I will check back tomorrow when I have time, I don't want to rush and goof anything up. tert

cor-el said

An error message about XPCOM missing or about platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder. This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files. You can do a clean reinstall to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

---

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

• download the Firefox installer and save the file to the desktop
  *https://www.mozilla.org/en-US/firefox/all/

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

• do NOT remove "personal data" When you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

• it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling
• http://kb.mozillazine.org/Uninstalling_Firefox

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data When you uninstall and reinstall or update Firefox, but make sure NOT to remove personal data When you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then you can create a new profile to test if your current profile is causing the problem.

---

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

Hi cor-el, Thank you so much for the quick response and information. I am not real comfortable disabling my security software. I will have to wait to try any attempts to fix it until tomorrow, but at least now I think I will be able to fix the problem. Thank you again for your help and I will be sure to reply with what worked to fix it or that I still need help. tert

What security software do you have?

tert said

Hi, I searched all over and was not able to find a solution to my problem. I can't access firefox at all. I keep getting this error messages: The procedure entry point?DllBlocklist_SetDllServices@@YAXPEAVDIIServicesBase@detail@mozilla@@@Zcould not be located in the dynamic link library C:\Program Files (x86)\Mozilla Firefox\xul.dll and Couldn’t load XPCOM I am hoping there is a way to fix it without losing everything. Thank you in advance for your time and assistance. T

Pkshadow said

Find and copy your Profile :

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

then uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do : (for the future do below since can not open Firefox)

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Hi, I finally had time to devote to fixing the problem and wanted to thank you. I have firefox again and did not lose anything that I can tell so far. Your solution was actually quick and easy and I can't thank you enough. Hopefully the rest of my unrelated computer issues will be as easy to fix ;) tert