Are you browsing in a private window? Make sure to allow the extensions to run in private windows: Extensions in Private Browsing.

Note that the Troubleshooting Information shows that those two extensions are disabled.

You can try "Clear the startup cache..." via the "Help -> More Troubleshooting Information" (about:support) page.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

You can check for problems with the extensions registry files in the profile folder.

Try to reset the extensions registry and rename extensions.json (extensionsOLD.json) and rename/remove compatibility.ini in the Firefox profile folder with Firefox closed.

• https://support.mozilla.org/en-US/kb/Profiles

New files will be created when required.

See "corrupt extension files":

• https://support.mozilla.org/en-US/kb/unable-install-add-ons-extensions-or-themes

You can check for possible updates in case of issues.

• click the cogwheel (left of the Search bar) on the about:addons page to "Check for updates"

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Are you browsing in a private window? Make sure to allow the extensions to run in private windows: Extensions in Private Browsing.

im not use private window.

Note that the Troubleshooting Information shows that those two extensions are disabled. You can try "Clear the startup cache..." via the "Help -> More Troubleshooting Information" (about:support) page.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

You can check for problems with the extensions registry files in the profile folder. Try to reset the extensions registry and rename extensions.json (extensionsOLD.json) and rename/remove compatibility.ini in the Firefox profile folder with Firefox closed.

• https://support.mozilla.org/en-US/kb/Profiles

New files will be created when required. See "corrupt extension files":

• https://support.mozilla.org/en-US/kb/unable-install-add-ons-extensions-or-themes

You can check for possible updates in case of issues.

• click the cogwheel (left of the Search bar) on the about:addons page to "Check for updates"

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Thank you very much for your detailed information. I'm sorry, but there is no problem with the extension itself, I can't see the extension panel. I also checked regedit. I tried everything but it doesn't work. Can't you see the panel? It's the latest version of firefox developer.

I have an additional question, displayed when the extension is installed. Extensions can be found in the application menu You're not talking about the addon manager, are you? Description: Please tell me how to use it, as long as I can use the extended function. If possible, how to not show the add-on manager

See also:

• https://support.mozilla.org/en-US/kb/extensions-button

jscher2000 - Support Volunteer さん曰く

Are you browsing in a private window? Make sure to allow the extensions to run in private windows: Extensions in Private Browsing.

im not use private window.

Okay, but please allow them to run in private windows just to rule out that issue.

See also:

• https://support.mozilla.org/en-US/kb/extensions-button

Despite following this The add-on manager will open. I'm not even pinned to the toolbar and I have the extension enabled.

jscher2000 - Support Volunteer|Top 10 Contributor ↓ Displayed! thank you! But even though I'm not using private windows why is it not showing (Only those that are allowed for private windows are displayed in the list.) To be honest, for security reasons, I don't want to allow private windows, but...

Every window is a private window if you enabled "Never remember history" or "Always use private browsing mode" (browser.privatebrowsing.autostart set to true in about:config).

Every window is a private window if you enabled "Never remember history" or "Always use private browsing mode" (browser.privatebrowsing.autostart set to true in about:config).

I made it! But it's strange to begin with...lol Make this the second best answer. It was helpful! We will continue to develop using developer!