Fix Firefox Not Allowing Website Sign-In

Firefox can refuse a sign-in even when your password is right. A blocked cookie, a site permission, tracking protection, an out-of-date saved password, or an extension sitting on the login page will all stop the form from going through.

Work through the checks in order, test the login in a private window, and you will usually find the one setting holding the site back.

In this guide, I have covered:

When Firefox won’t let you sign in to a website

You type the right password, press the button, and nothing happens. The page reloads with the same form, or throws an error that never names the cause. That is the problem this page solves.

Most Firefox sign-in issues trace back to something the browser is holding back rather than a wrong password: cookies the site cannot store, a blocked site permission, a saved password that no longer matches, an extension sitting in the middle of the request, or site data left over from an earlier attempt.

Work through the checks in order. All of them apply to Firefox on Windows, macOS, and Linux. If the same login works in another browser, you are almost certainly looking at a Firefox setting or a stale profile.

Mozilla documents what sites keep on your computer in its cookie and website storage documentation, which is useful background before you change anything.

Check whether cookies are blocked for the website

Firefox has to store a cookie before many login forms will accept anything. Switch cookies off globally and the sign-in fails quietly, with no message pointing at the real cause.

1. Click the hamburger menu in the top right of Firefox and choose Settings.
2. Select Privacy & Security from the left sidebar.
3. Scroll down to the Cookies and Site Data section.
4. Confirm the selected radio option is "Accept cookies and site data from websites (recommended)" and not "Block cookies and site data".
5. If it was set to block, change it to accept, then close and reopen the affected tab.

You’ll know it worked when the site remembers your session after a reload, or at least stops complaining about cookies. Close the tab, open the site again, and submit the form once. Still failing? The block is probably site-specific, so move to the exception below.

RELATED: Clear Browser Cookies and Cache from the Mozilla Firefox

Allow cookies for the site that won’t sign you in

Your cookie setting can be perfect while a single domain sits on a block list you built months ago and forgot about. Add an exception for the exact domain where the login form appears, not a parent site or a subdomain you guessed at.

1. Click menu in the top-right of Firefox and choose Settings.
2. Select Privacy & Security from the left sidebar.
3. In the Cookies and Site Data section, click the Manage Exceptions… button.
4. Type the full site address (for example, https://example.com) in the Address of website field.
5. Set the Status dropdown to Allow for Session (not plain Allow).
6. Click Save Changes, then close the dialog.
7. Reload the site in the browser.

Reload the page once the exception is saved. You’ll know it worked when the form submits or the cookie warning disappears. If the page still refuses, leave the exception in place and check third-party cookies next.

Allow third-party cookies when the login runs on another domain

Many logins hand you off to a different domain for identity checks, CAPTCHA, or payment verification. The form loads on the site you know, but the error appears after you press Continue. That gap is where third-party cookies matter.

1. Click the hamburger menu at the top right of Firefox and choose Settings.
2. Select Privacy & Security from the left sidebar.
3. Under Enhanced Tracking Protection, choose Custom.
4. Tick the Cookies checkbox, then pick All third-party cookies from the dropdown that appears.
5. Open the shopping site in a new tab, click the shield icon, and confirm ETP is on but the cookie setting now allows the store's embedded scripts to run.

Try signing in again. You’ll know it worked when the redirect finishes and you land back on the site already signed in. If your credentials are still rejected, the cookie path is fine and the problem sits further down this list.

Check the site’s privacy permissions

The padlock panel shows exactly what Firefox is blocking on the page in front of you. Open it from the login page itself, not from a different tab, so the permissions belong to the right site.

1. Open the affected website and go to its sign-in page.
2. Click the padlock in the address bar.
3. Open the site’s connection information or permissions panel.
4. Review the permissions for cookies and site data.
5. Change a blocked setting only if the site’s sign-in flow requires it.
6. Reload the page and try signing in again.

If the site posts its own warning about blocked cookies or privacy permissions, trust that message and use the controls the site provides. You’ll know the panel is clean when nothing shows as blocked for that domain. Undo any change that made no difference before you test the next item.

Turn off Enhanced Tracking Protection for the affected site

Enhanced Tracking Protection blocks cross-site scripts by design. A few login systems treat those scripts as essential, which is why a page can look perfectly normal and still refuse to sign you in.

1. Open the website that fails to load in Firefox.
2. Click the shield icon to the left of the address bar.
3. Toggle the switch labeled "Enhanced Tracking Protection is ON for this site" so it moves to OFF.
4. Wait for Firefox to reload the tab automatically, then try the page again.

Reopen the login page and try again. You’ll know it worked when the form submits with protection off for that domain. If nothing changes, switch the site back to standard protection and keep testing. Leave the exception on only for sites you trust.

Check saved passwords for the website

A stale saved password is easy to miss, because Firefox fills it in for you and you never see the value. Change your password on a phone or in another browser and the stored entry can be months out of date.

1. Open the Firefox menu .
2. Select Passwords from the menu.
3. Find the website in the saved logins list.
4. Open the entry for the affected account.
5. Check the saved username and update the password if you have changed it recently.
6. Return to the website and try the updated credentials.

Do not delete a saved password until you are sure of the current one. You’ll know the entry was the problem when typing the password by hand works and the autofilled version does not. If both fail, the saved login is innocent.

Test the sign-in with a private window

A private window opens the site with none of your normal profile data and, by default, no extensions. That makes it a fast yes-or-no test. If the login works there, the cause lives in your everyday profile.

1. Press Ctrl + Shift + P (or Cmd + Shift + P on macOS) to open a Private Window.
2. Visit the site that was not accepting cookies.
3. If it works here, return to the normal window and run Troubleshoot Mode to disable extensions temporarily.

When the sign-in succeeds in private but fails in your normal window, you have your answer: profile data or an extension is involved. Go back and test site data, extensions, and tracking protection one at a time. If it fails in both windows, cookies and extensions are less likely to be the culprit, so jump ahead to Troubleshoot Mode.

Clear site data for the affected website

Half-finished logins leave broken cookies behind. Clearing data for the one domain where the form appears gives Firefox a clean start without signing you out everywhere else.

1. Open the menu at the top right of Firefox and click Settings.
2. Select Privacy & Security from the left sidebar.
3. Scroll to the Cookies and Site Data section and click Manage Data….
4. Type the site's name into the Search websites field to find it faster.
5. Select the site, then click Remove Selected.
6. Click Save Changes and confirm the prompt.
7. Reopen the site in a new tab and pin it again.

Open a fresh tab rather than reloading the old one, then try again. You’ll know it worked when the site asks for your username and password as if you were new. Expect to be signed out of other sessions for that site, and a second verification prompt is normal.

If you want to tidy up stored data across more than one site, the steps to delete site data without deleting cookies elsewhere in Firefox walk through the same storage panel in Settings.

Check for extension interference

Privacy blockers, password managers, and antivirus add-ons all inspect login pages. Any one of them can strip a script the form depends on, and the site will fail without ever naming the culprit.

1. Click the hamburger menu and select Add-ons and themes.
2. In the left sidebar, click Extensions.
3. Use the blue toggle next to each extension to disable it. Start with ad blockers, tab managers, and any extension you installed in the past few weeks.
4. Restart Firefox from the hamburger menu .
5. Use Firefox normally for a few minutes, then check about:performance. If usage dropped sharply, re-enable extensions one by one to find the offender.

Reload the website and try to sign in. You’ll know it worked when the form submits with extensions off. Turn them back on one at a time, testing the login after each, and you will find the single extension at fault.

Use Troubleshoot Mode for a clean test

Troubleshoot Mode starts Firefox with extensions and some custom settings switched off, while keeping your bookmarks, history, and passwords. It is the closest thing to a fresh install without losing your profile.

1. Click the hamburger menu at the top right of Firefox.
2. Click Help.
3. Select Troubleshoot Mode….
4. Click Restart in the confirmation dialog.

Sign in while Troubleshoot Mode is running. You’ll know it worked when the login goes through there but fails in your normal window, which points straight at an extension or a setting. Close the mode without applying changes permanently, then track down the individual cause.

What to do if the sign-in still fails

Read what the page actually says. A blocked cookie, a redirect loop, a script that never loads, and a certificate warning each point somewhere different. The browser console names the one you have: F12 on Windows or Linux, Cmd+Option+I on macOS.

Check your computer’s date and time as well. A clock that has drifted far enough breaks certificate checks and some authentication tokens, and the site will blame your password.

If the login works in another browser, or in a Firefox profile with almost no extensions, go back over the site data and privacy settings above. If it fails everywhere, the account or the service is the problem, not Firefox. The guide to fixing a site that loads in other browsers but not Firefox covers the remaining browser-side checks.

Mozilla Support’s thread on reported Firefox sign-in failures is worth a read if your case looks unusual.