Then I get a google window to sign into my gmail email account - it has correct email address shown.. I enter correct password

That part is correct because Google needs to know you really is you to allow Thunderbird access and at this point it creates an Oauth token which gets stored in Thunderbird passwords area.

You need to check a few things.

Then that 400 error sounds like you may need to enable cookies Make sure you have cookies allowed In Thunderbird Settings > Privacy & Security Web Content

• Select 'Accept cookies from sites'
• Click on 'Exceptions: button
• Add this: https://accounts.google.com
• Set it to 'Allow'
• click on 'Save Changes'

If you use a program that uses the localhost eg: Apache or Xampp typically used by people who manage websites then you need to switch it off until the oauth token has been set up.

If you use a VPN then switch it off because gmail will not like it and will think someone is trying to hack your account.

Thanks Toad Hall I setup cookies as you suggested...no change. Restarted Tbird a few times too I can login to my gmail account via google as normal so can't understand when Tbird keeps on asking for my correct gmail password.( I resorted to setting up the Gmail account manually) Also strange is that my gmail account in Thunderbird only shows an inbox and no Sent, Junk boxes etc as normally expected. I rechecked all the settings and they seem ok so my gmail account in Tbird which always worked in past..now seems stuffed!

Do you or others have a plan B ??

In the begining for all those years - did you use a pop or imap account ?

Then you said "I deleted the gmail account.....( I resorted to setting up the Gmail account manually)" Did you set up a new gmail IMAP account or a POP account?

So what exactly is the current situation....Please post current settings: In Thunderbird

• Help > Troubleshooting Information
• Scroll down to 'Mail and New Accounts
• Copy all the data
• Paste it into this forum question.

You said - Checked in webmail - gmail settings and imap is ticked - pop is not. In gmail webmail account accessed via a browser.

• 'Settings' > 'See all settings'

Select the tab - 'Forwarding and Pop/Imap'

• Pop download -

If you want to use Pop then you need to select 'Enable pop for all mail'

• Imap Access - You say this is selected: 'Enable imap'

Are folders/labels allowed to be shown?

• Select the 'Labels' tab
• For all folders that need to be shown in imap:
• Select the checkbox 'Show in Imap'

Q: Have you enabled the gmail 2 step verification ? If yes, then in Thunderbird you cannot use 'Authentication Method: Oauth' because gmail will expect an app specific password - not the normal password which you only use to log onto webmail account.

If you want to use 'Authentication Method : Oauth' then uncheck/switch off/kill 2 step verification. It is recommended by gmail that Oauth is used.

You said - but.. in "View password"..there was no details at all for this gmail account. At least that does explain why you are asked for password. Previously accounts used a normal password, so would have see: For a Pop account - mailbox://google account..... For an Imap account - imap://google account..... The smtp for both: - smtp://google account....

Those who swapped over to use Oauth would see this line: oauth://accounts.google.com....

re :"400 Thats an error... The server cannot process the request because its malformed. It should not be retried. Thats all we know"

It is possible that the server generated this error because it's got expired/corrupted browser cookies.

You probably have set up some of the following - but I'm retyping anyway with added info - these settings are designed to keep everything open for google to set up.

In Thunderbird Settings > Privacy & Security Web Content

• Select 'Accept cookies from sites'
• Accept third party cookies - 'Always'
• DO NOT select the checkbox 'Send websites a 'Do Not TRack' signal that you do not want to be tracked.
• Click on 'Exceptions: button
• Add this: https://accounts.google.com - please check you have spelt that correctly
• Set it to 'Allow'
• click on 'Save Changes'

Then click on 'Show Cookies' button Let's try removing any cookie that mentions google. Thus allowing them all to get reset.

Whilst in this area: Current Situation DO you still have nothing saved for google in 'Saved PAssword' ?

Then clear Disk Space cache

• Settings > General
• Scroll to 'Disk Space' section
• click on 'Clear Now'

Thanks Toad Hall You put a lot of effort into this prob...somehow it just started working., I had followed your method, even got a new gmail password and zilch..just got the 400 error and when set up as a manual setup got the 'enter password' but strangely there was only an inbox attached to the gmail account and no imap listing in passwords -just the smpt.

After many reboots, cache cleans, TB restarts etc..I tried once more and Google accepted my password and my gmail account had all the other boxes rather than just inbox and in the passwords there was now an Oauth setting for google. How fixed ???? no idea.. Really appreciate your help at a tech level most users would have no idea of.

Cheers