If you find that you cannot log in to a website that requires a username and password, follow the steps described in this article.

• If you can log in to a website manually, but cannot save or use saved usernames and passwords, see Usernames and passwords are not saved.

Enable cookies for the website

Make sure that cookies are enabled for the site in question:

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.

2. Select the Privacy & Security panel and go to the History section.

3. In the drop-down menu next to Firefox will, choose Use custom settings for history.
4. Make sure Accept cookies from sites is selected.
5. Make sure Accept third party cookies is selected.
   • Third-party cookies and Firefox tracking protection can cause problems with some websites. Enable this setting to rule it out as a cause for your problem.
6. Click Exceptions....
7. Make sure the site you're trying to access isn't listed.
   • If it is listed, click on its entry, then click Remove Site.

If you changed any settings, try logging in to the site again.

Clear history for that site

The cookies and temporary data already stored on your computer may be causing the problem. Delete them, then test for your problem:

1. Click the menu button to open the menu panel. Click History and then click the Manage history bar at the bottom to open the Library window.
2. At the top right corner, type the name of the website you wish to forget in the Search History field, and press EnterReturn.
3. In the resulting list, right-clickhold down the Ctrl key while you click on the site you wish to forget, and select Forget About This Site.
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4. Close the Library window.

Clear all cookies and the cache

If deleting cookies for the site with the problem did not fix the error, clear all the cookies stored on your computer and clear the Firefox cache:

1. Click the menu button to open the menu panel.
2. Click History and select Clear Recent History…
3. In the Time Range to clear: drop-down, select Everything.
4. Below the drop-down menu, select both Cookies and Cache. Make sure other items you want to keep are not selected.
5. Click OKClear Now.

Check Extensions and Plugins

Some extensions can cause problems with logging in to websites, especially extensions associated with certain websites. For example:

• If you cannot log in to Yahoo! and you use a Yahoo! Toolbar extension, try disabling it using the instructions in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article, restarting Firefox and then following the steps above to clear cookies and cache again.
• If you cannot log in to Gmail and you use a Google extension, try disabling it and then following the above steps to clear cookies and cache before trying to log in again.
• Other extensions may also cause login problems. To determine if they are the cause, see: Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

Some plugins can also cause problems logging in to websites. See the Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems article for instructions on how to determine whether a plugin is causing your problem.

Remove corrupt cookies file

If you cannot log in to websites after removing the cookies associated with it, clearing your Firefox cache, and trying with your extensions and plugins disabled, and have checked security software, you may have a corrupt cookies file in your Firefox profile folder.

1. Open your profile folder:

   • Click the menu button , click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
   • Under the Application Basics section next to Profile FolderDirectory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.
   Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

2. Click the Firefox menu and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu and select Quit.
3. Delete the cookies.sqlite file and any cookies.sqlite-journal files.
4. Restart Firefox.

Includes information from Websites report cookies are disabled (mozillaZine KB)