If you are using a VPN then switch it off. If you are using a program that uses 'localhost' eg: Apache then switch it off whilst trying to set up gmail account. In Firewall, make sure thunderbird.exe (program) is set up as an allowed program.

In gmail webmail account accessed via a browser, please make sure account is set up as Imap enabled. If you have set up to use 2 step verification then switch it off so you can set up using oauth2.

In Thunderbird Check javascript is enabled:

• Settings > General
• Scroll to bottom and click on 'Config Editor'
• In search type: javascript
• check: javascript.enabled = true

In Thunderbird make sure cookies are enabled.

• Settings > Privacy & Security
• Under 'Web Content' section
• Select checkbox 'Accept cookies from sites'
• Accept third party cookies: 'Always'
• Keep until: 'they expire'
• click on 'Exceptions'
• set up 'https://accounts.google.com' as 'Allow'
• click on 'Save Changes'

I'm assuming you have not got any gmail account set up but whilst in this area double check nothing is saved in the passwords.

• Settings > Privacy & Security
• under 'Passwords' section
• click on 'Saved Passwords'
• If you see any mention of the gmail account, select each line and click on Remove.

• New > Existing mail account
• Enter name
• Enter full gmail email address
• Enter password - this is the same one you use to access webmail account
• Select to remember password
• Click on 'Continue'
• Thunderbird will locate the server settings and by default will set up to use IMAP.

You should see: Incoming : IMAP

• Server name: imap.gmail.com
• Port: 993
• Connection Security: SSL/TLS
• Authentication Method: Oauth2
• Username: full gmail email address

Outgoing SMTP

• Server name: smtp.gmail.com
• Port: 465
• Connection Security: SSL/TLS
• Authentication Method: Oauth2
• Username: full gmail email address

• So if you do not want IMAP then you will need to change the Incoming 'protocol' to POP3 option.
• click on 'Done'

You should get a pop up with google asking to confirm it really is you. Enter gmail address and password to allow thunderbird access to server.

Hi Todd. Thankyou for taking the time to reply. I had done much of what was suggested however when through and thoroughly checked the list you've suggested. I am getting the same message :(

Had you ever set up the 2 step verification ? Did you need to go into webmail account and switch it off?

Are you able to login to the gmail webmail account? Please confirm you can do this because that will prove you know password is correct.

Try this modification - do all the same as before but when it comes creating the account do not enter password.

• New > Existing mail account
• Enter name
• Enter full gmail email address
• DO NOT Enter password - leave blank.
• Select to remember password
• Click on 'Continue'

Thunderbird will locate the server settings and by default will set up to use IMAP. When you click on 'Done' you should then get the google prompt at which point you would need to enter the same password you use when loging on to webmail.

@Toad-Hall

I did have 2 step active on my account but had used a browser to switch it off. That aside the process of entering all the details minus the password FINALLY gave me the prompt and its all fixed! Legend:) Cheers

Good to hear you've access and thanks for letting me know the process which worked.