Please provide a screenshot of that message where TalkTalk webmail is advising Firefox users to use a different browser. Or a link to a webpage where TalkTalk is saying that.

That issue pops up from time to time over that last 4 -5 years, going back to the days of Firefox 4.0. It may be a "site issue" caused by corrupt cookies or cached history from prior to the version upgrade. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Click the menu button , choose History, and then "Clear Recent History...".
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the "Clear Now" button.

Did this fix your problems? Please report back to us!

Is this a problem with a secure HTTPS connection?

The website may try to fallback to a lower TLS version in a way that is no longer allowed in current releases or may be using a deprecated cipher suite.

You can open the about:config page via the location/address bar and use its search bar to locate this pref:

• security.tls.insecure_fallback_hosts

You can double-click the line to modify the pref and add the full domain (TEXT) to the value of this pref. If there are already websites (domains) in this list then add a comma and the new domain (no spaces). There should only be domains separated by a comma in the Value column (example.com,www.example.com).

If this helps then you can contact this website and ask them to look into this and update their security.

• https://developer.mozilla.org/en-US/Firefox/Releases/36/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/37/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/38/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/39/Site_Compatibility#Security

the-edmeister said

Please provide a screenshot of that message where TalkTalk webmail is advising Firefox users to use a different browser. Or a link to a webpage where TalkTalk is saying that. That issue pops up from time to time over that last 4 -5 years, going back to the days of Firefox 4.0. It may be a "site issue" caused by corrupt cookies or cached history from prior to the version upgrade. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Click the menu button , choose History, and then "Clear Recent History...".
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the "Clear Now" button.

Did this fix your problems? Please report back to us!

Hi Thanks for the feedback, however that didnt work . The page you asked about is www.talktalk.co.uk/mail/?check_cookie=1

OK, they acknowledge that they have a problem with Firefox, Seeing that they don't use a HTTPS connection initially and for their login page, I suspect what cor-el mentioned - an issue with "fallback to a lower TLS version in a way that is no longer allowed in current releases or may be using a deprecated cipher suite." We can't verify this issue without having valid login credentials to proceed with.

IMO, TalkTalk needs to update their security at that website or you need to set the security.tls.insecure_fallback_hosts exception that cor-el mentioned. Of course you could just use a different browser as TalkTalk says; a browser whose security standards are lower than Firefox - but that would be a "temporary fix", until "that other browser" gets serious and fixes their TLS ...

OK understood . Here is the error message after login attempt

An error occurred during a connection to webmail.talktalk.co.uk. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. (Error code: ssl_error_weak_server_ephemeral_dh_key)

   The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
   Please contact the website owners to inform them of this problem.

This is an issue of the site. Send this link to the webmaster:

https://developer.mozilla.org/en-US/Firefox/Releases/39/Site_Compatibility#Security

Firefox 39 includes a fix for the Logjam vulnerability and has disabled cipher suites that are involved with the Logjam attack.

See also:

• http://arstechnica.com/security/2015/05/https-crippling-attack-threatens-tens-of-thousands-of-web-and-mail-servers/

Logjam: How Diffie-Hellman Fails in Practice: https://weakdh.org/

Just from today I cannot access my talk walk webmail account I get message stating "undefined emails" Also possibly not related my, file- edit- tools history-bookmarks tool bar has gone missing. I can access my webmail internet explorer no problem which indicates a browser problem. What I do not need is a long complicated rigmarole list of instructions on how to sort out firfox. I like this browser and would like to keep using it , so please get this problem sorted out. I have tried to reset browser but nothing happens. So HELP

Hi dearboy

Could you please start a new thread for your question?

Then you can provide more information like your operating system and installed extensions and installed plugins.

• [start a new thread]
• [/kb/Using+the+Troubleshooting+Informatio...]

In case of crashes also please add some recent crash IDs that start with a "bp-" prefix.

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

sorry for delay in responding been away for xmas. I am operating windows 10. I have Firefox 44.ob1 recently installed. the problem seems to have arisen from its installation? On accessing my webmail, there is in the inbox for emails "undefined). I can access webmail from IE no problems. Told by talk talk that its a browser problem (in this case firefox). Have tried to reset firefox to no avail. I do not wan to loose bookmarks etc by undertaking "clean" reinstall , Unless there is no other option. would system restore sort this out. Very frustrated. Do not want an overcomplicated method to sort this, I am not very computer adept.!!, I would like to continue using fire fox (not my default browser) cor-el please help with this problem