Thunderbird has made alterations so now both POP and IMAP accounts can use OAuth2 for gmail. Have you done all of the following?

• Select 'Menu app icon' > 'Preferences' > 'Privacy & Security '

Under 'Web Content'

• Select 'Accept cookies from sites'

It may also be a good idea to make exception:

• Click on 'Exceptions..' button
• Enter: https://accounts.google.com
• Set to 'Allow'
• click on 'Save Changes'

Now make changes to Account Settings:

• Right click on gmail pop/imap account name in Folder Pane and select 'Settings'

This opens the Account Settings in new tab The pop/imap account name should be selected Look bottom right for Outgoing Server (SMTP)

• Click on 'Edit Server _SMTP' button
• Set Authentication Method : OAuth2
• Click on OK

Now set the incoming authentication:

• select 'Server Settings' for gmail account
• Set Authentication Method : OAuth2

Exit Thunderbird and wait a few moments for background processes to complete Start Thunderbird

Gmail will prompt you to enter gmail email address and normal password you use to access webmail account. Follow instructions. It will ask this to allow Thunderbird to access server.

An Oauth token will get stored in Thunderbird - same place as passwords and from then onwards Thunderbird will use it to access server.

Additional:

Note: Gmail may advise to switch on 2 step verification. This is not necessary because you are using OAuth.

Some people have needed to remove the old stored passwords.

• Menu app icon > Preferences > Privacy and Security
• Under 'Passwords' section
• Click on 'Saved Passwords'
• Select the mailbox://(if pop), imap:// (if imap) and smtp:// lines and click on 'Remove'.

Restart Thunderbird.

Some people run a localhost server eg: Apache This must be switched off and then retry. You should be able to use the google prompt. You can switch Apache back on afterwards. Note: In some Linux systems Apache may have been auto installed.

If you find you keep being asked for password and in :

• 'Menu app icon' > 'Preferences' > 'Privacy & Security '

You discover passwords and cookies are not being saved then do this:

• Menu app icon > Help > More Troubleshooting Information
• Under 'Application Basics' - Profile Folder - click on 'Open Folder'

This opens a new window showing the contents of your current in use profile name folder.

• Exit Thunderbird now - this is important.

Look for the following files and delete them.

• cert8.db - obselete file
• key3.db - obselete file
• pkcs11.txt (some people report this file missing)
• secmod.db - obselete file
• session.json
• xulstore.json

NOTE: Do NOT delete:

• key4.db
• cert9.db
• logins.json

Start Thunderbird New pkcs11.txt, session.json, xulstore.json files will get created.

Retry entering password etc at prompt.

I have done all of this. When I go to add a gmail account it keeps giving me a secure connection failed

I just wasted a full two hours running in circles trying to follow the recommendations of the "experts" above I know NOTHING of emails (and plan to stay ignorant)

The answer is in a reddit post: https://www.reddit.com/r/Thunderbird/comments/v7ziud/how_i_fixed_oauth_problems_in_a_tb_profile_with_2/ "The gmail popups won't let me enter passwords... it just refreshes over and over with the email account box. Yes the accounts are still valid and working."

Go to Thunderbird -> Preferences -> Privacy and Security In the Web Content section:

ACCEPT ALL COOKIES - it is as yet unclear whether should be only all third party etc. and how long to keep them - can one be minimalist with these cookies

This IMMEDIATELY worked and all of my mail since June 6th downloaded

I just wasted a full two hours running in circles trying to follow the recommendations of the "experts" above I know NOTHING of emails (and plan to stay ignorant) The answer is in a reddit post: https://www.reddit.com/r/Thunderbird/comments/v7ziud/how_i_fixed_oauth_problems_in_a_tb_profile_with_2/ "The gmail popups won't let me enter passwords... it just refreshes over and over with the email account box. Yes the accounts are still valid and working." Go to Thunderbird -> Preferences -> Privacy and Security In the Web Content section: ACCEPT ALL COOKIES - it is as yet unclear whether should be only all third party etc. and how long to keep them - can one be minimalist with these cookies This IMMEDIATELY worked and all of my mail since June 6th downloaded

The information I gave did say to 'accept all cookies'. The information was also using a Windows OS. Unless someone states they are using a different OS then I assume it is Windows as it is the most commonly used OS. If you are using a different OS eg: Linux, then please remember to mention this just in case other Linux users locate the information as it will be helpful.

I have done all of this. When I go to add a gmail account it keeps giving me a secure connection failed

Check the Firewall is not blocking Thunderbird. Maybe the Firewall thinks an update is a completely different program.

Exit Thunderbird and access the Firewall. The Firewall may be provided by the OS or be controlled by an Anti-Virus product.

Thunderbird needs to be in the list as an allowed program. If Thunderbird is already an allowed program, then block it, ok it. Then go back into the Firewall and set it up as allowed again and ok it.

What Anti-virus are you using ? What OS are you using?

Initially you said the gmail account quit working and now you are talking about adding a gmail account. Did you remove the gmail account and try to add it back ? Or are you now talking about a different gmail address ?

Are you trying to add a pop or imap account ?

Let's assume it is an imap account: These are the server settings you should be using.

• Incoming Server name: imap.gmail.com
• Port : 993
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• User name: full gmail email address

Outgoing server name: Server Name: smtp.gmail.com

• Port : 465
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• User name: full gmail email address

I am having the same problem and have tried every fix out there with no luck I disabled Kaspersky and that did not help either. I'm so frustrated because I love my Thunderbird. Please help

I am having the same problem and have tried every fix out there with no luck I disabled Kaspersky and that did not help either. I'm so frustrated because I love my Thunderbird. Please help

When you post into someone elses question you are in effect asking the person who posted the question for any help. Gmail connection issues may not be a single fix. There are many possibilities and it only takes one issue to mess up everything. Please start your own question and this time provide information. What OS you use ? What version of Thunderbird are you using? Provide info/images that show the current Account Settings > Server Settings and also the Outgoing smtp server settings. Assume no one knows precisely what you have tried nor in what order. Thanks.