Make sure to allow cookies in Thunderbird. https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20

Thank you for your reply. And appreciate your help.

I checked my settings. And I tried to two settings, but The situation did not improve.

What is your anti-virus software?

Thank you for your reply. I use windows defender, and setting is default.

Try to start Windows 10 in safe mode with networking enabled. Does the problem go away?

Windows safe mode disables anti-virus software. This is a troubleshooting step, not a solution.

Thank you for your reply.

I could not do that, because I use wifi tethering with mobile phone.

So, I tried to off windows defender. But the situation did not improve.

I'm running out of ideas. One last thing you can try: Create an exception in your anti-virus software for the Thunderbird profile folder so that the real-time scanner will not scan it. To find out the location of the profile see https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_how-to-find-your-profile

Thank you for your kindness.

I tried it, but the situation did not improve.

I will review the settings again. I appreciate for your help.

The image you posted when trying to create imap mail account did not have the 'Remember Password' checkbox selected, so token is not saved. Suggest you select that checkbox.

The password you entered - is it a normal password or have you switched on 2 step and the password you entered is an app specific password ?

You are setting up to use Authentication Method: Oauth2 Do not use 2 step verification - switch it off. Do not use an app specific generated password. Just use normal password. Can you confirm you are NOT using 2 step nor app specific generated password ?

Thank you for your reply. I checked some settings and I tried to your way. But the situation did not improve.

I love this app, so I am really sad...

Does the Firewall have Thunderbird set up as an allowed program ? If no then Exit Thunderbird and set up Thunderbird as allowed program in Firewall.

If yes, then see if it has multiple entries. Exit Thunderbird Remove the entries and reset as allowed program again Or if only one then disable/block , ok it, access Firewall again and reset to allowed.

Do you run any type of local host server app eg: Apache If yes, then switch it off and try again to create gmail account.

Do you run any type of VPN? If yes, then switch it off and try again to create gmail account.

Thank you for your reply. This is my situation.

>Does the Firewall have Thunderbird set up as an allowed program ? >If no then Exit Thunderbird and set up Thunderbird as allowed program in Firewall. Yes. (picture1)

>If yes, then see if it has multiple entries. >Exit Thunderbird >Remove the entries and reset as allowed program again Or if only one then disable/block , ok it, access >Firewall again and reset to allowed. I don't khow how to check and remove that setting.

>Do you run any type of local host server app eg: Apache >If yes, then switch it off and try again to create gmail account. I don't use local host server.

>Do you run any type of VPN? >If yes, then switch it off and try again to create gmail account. I don't use VPN.

Please try this:

• Menu app icon > 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 reported this file was 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.

then try again to create the gmail.

Thank you for your reply.

I tried to these.

1. Deleted these files. (attached photo) 2. Rebooted thunderbird. 3. Created the Gmail.

But the situation did not improve.

When you try to create the gmail account (remember you do need to select 'Remember Password'), you enter all details and Thunderbird locates the configuration server settings, when you click on 'Create Account'/'Done' ..... - Do you get a google pop up browser looking window asking you to enter gmail email address and normal password in order to allow Thunderbird access?

I ask this because it has never been mentioned.