Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button ≡, then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Thanks. This is part of the information. There is a lot more beginning with EGL_VENDOR: Google Inc. (Intel)

 Application Basics

   Name: Thunderbird
   Version: 140.4.0esr
   Build ID: 20251010020716
   Distribution ID:

   Update Channel: esr
   User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Thunderbird/140.4.0
   OS: Windows_NT 10.0 19045
   OS Theme:

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
   Fission Windows: 0/0
             Enabled by default
   Remote Processes: 3
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false
   Memory Size (RAM): 7.9 GB
   Disk Space Available: 352 GB

 Mail and News Accounts

 Libraries

     Library
     Status
     Expected minimum version
     Version in use
     Path

       RNP (OpenPGP)
       OK
       0.17.1
       0.17.1.MZLA.140.4.0esr.botan
       C:\Program Files\Mozilla Thunderbird\rnp.dll

       OTR
       Failed to load. OTR chat encryption will not work.
       -
       -
       -

 Calendar Settings

   Home

     Name
     Value

     Name:
     Type: storage
     Disabled: true
     Username:
     URI:
     Refresh Interval:
     Read-only:
     Suppress Alarms:
     Cache Enabled:
     iMIP Identity:
     iMIP Disabled:
     iMIP Account:
     Organiser Id:
     Force Email Scheduling:
     Popup Alarms Supported:
     Alarms on Invitation Supported:
     Max Alarms Per Event:
     Attachment Supported:
     Max Categories:
     Privacy State Supported:
     Priority Supported: true
     Event Supported:
     Task Supported:
     Local Time Supported:
     UTC/GMT Supported:
     Auto-Scheduling Supported:

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

     Isolated Web Content: 1
     RDD: 1
     GPU: 1

 Add-ons

     Name
     Type
     Version
     Enabled
     Location
     ID

       System theme — auto
       theme
       1.4.1
       true
       app-builtin
       default-theme@mozilla.org

       Dark
       theme
       1.3
       false
       app-builtin
       thunderbird-compact-dark@mozilla.org

       Light
       theme
       1.3
       false
       app-builtin
       thunderbird-compact-light@mozilla.org

 Security Software

   Type: Name

     Antivirus: Microsoft Defender Antivirus
     Antispyware:
     Firewall:

 Legacy User Stylesheets

   Active: false
   Stylesheets: No stylesheets found

 Graphics

     Features
     Compositing: WebRender
     Font Visibility Debug Info: Windows Platform
     Asynchronous Pan/Zoom: wheel input enabled; scrollbar drag enabled; keyboard enabled; autoscroll enabled; smooth pinch-zoom enabled
     WebGL 1 Driver WSI Info: outOfProcess: false

inProcess: true

You skipped the Mail Account portion. This is what's needed.

When I copied the information to the clipboard, there were 22 000+ characters - a lot more than in the table displayed on the screen and more than I could post here. But I did send this:

 Mail and News Accounts

 Libraries

     Library
     Status
     Expected minimum version
     Version in use
     Path

       RNP (OpenPGP)
       OK
       0.17.1
       0.17.1.MZLA.140.4.0esr.botan
       C:\Program Files\Mozilla Thunderbird\rnp.dll

       OTR
       Failed to load. OTR chat encryption will not work.

There was nothing in the "Mail and News Accounts" section. I'm sorry it's being so complicated

This is the screen when I try to connect to Gmail. I changed the password to an "app password".

There was nothing in the "Mail and News Accounts" section. I'm sorry it's being so complicated

It's not complicated. So you're just trying to set up an existing account in Thunderbird. That wasn't obvious from your OP. It helps being precise.

Make sure cookies are allowed in Thunderbird. Don't use a VPN when attempting to authenticate. Also make sure no software is occupying TCP port 80 on localhost, e.g. like a local web server.

In Settings - General, uncheck the option 'Create accounts in the new Account Hub'.

I changed the password to an "app password".

With OAuth authentication you must use the main account password, not an app password.

Having said that, it is a really bad idea to post your password to a public forum. So you want to remove those screenshots with the password.

My original post said "I have tried many times to get Thunderbird to connect to my Gmail account. " I have changed the screenshot - thanks for pointing that out. I'm not using a VPN. I can't see how to allow cookies in Thunderbird - it's a program on my PC, not a website. I tried with the main account password - that didn't work but I'll try it again. I was using xampp which may have been using port 80. I have stopped xampp. The option 'Create accounts in the new Account Hub'. is unchecked - I never checked it. I'll have changed the password. It's now stuck saying "Looking up configuration. Probing server" .

It's ok if you want to leave it for now. Thanks for your efforts so far.

My original post said "I have tried many times to get Thunderbird to connect to my Gmail account. " I have changed the screenshot - thanks for pointing that out. I'm not using a VPN. I can't see how to allow cookies in Thunderbird - it's a program on my PC, not a website. </blockqauote> So is you browser, it also has an option in settings to allow or disallow cookies.

I tried with the main account password - that didn't work but I'll try it again. I was using xampp which may have been using port 80. I have stopped xampp. The option 'Create accounts in the new Account Hub'. is unchecked - I never checked it. I'll have changed the password.

I would guess we have an antivirus problem. The settings you posted way back were correct. An attempt to connect using them should initiate a series of web pages from Google asking for your password and permission for Mozilla Thunderbird to access your email, contacts etc at Google. Do you get these "Popups"? I have frequently seen folk on this forum complain about them and either close them or ignore them and then complain that Thunderbird is not getting their mail, so I have to ask. Are you one of them.

What antivirus are you using? While a password is included in the account setup, it is not used at all in an oauth authentication process which must be used for google gmail. You would be just as well leaving it out entirely.

It's now stuck saying "Looking up configuration. Probing server" . It's ok if you want to leave it for now. Thanks for your efforts so far.

There should be no server probing going on. Thunderbird should lookup the settings here https://autoconfig.thunderbird.net/v1.1/gmail.com and use them. That there is probing going on would indicate a firewall issue blocking that lookup.

We come back to my assumption you have an antivirus issue as most of those these days come with these fancy anti phishing and scam modules that actively block the probing. However as I said Thunderbird should not get to that point because it looked up the settings. For that to fail indicates a software firewall issue another antivirus component. I have a pet hate going on with Norton as I have a friend that uses it and have never managed to set up an account on his system without disabling whole chunks of it. Something called SONAR blocked the new account wizard, despite it not having anything to do with email according to Norton. It has a VPN component with a longstanding habit or just re-enabling itself. Google/Gmail does not do well with a VPN as christ1 alluded. Essentially if you have an antivirus other than Microsoft defender it is suspect

I have changed the screenshot

There is another one.

I can't see how to allow cookies in Thunderbird

At the top right of the Thunderbird window, click the menu button ≡ > Settings Type 'cookies' (without the quotes) into the search box at the top right.

I finally got it to work but set up as POP not IMAP. I wanted to use IMAP.

The only anti-virus on my PC is Windows Defender. Does Thunderbird support imap with gmail? Anyway, I'll just see how it goes. My main reason for using Thunderbird is to have incoming messages sorted into folders using rules, as in Outlook.