Are you trying to login using an App password instead of your Google account password?

Also, 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.

Gmail uses Oauth2, so you need to make sure a few things are set up correctly first. Please work through everything - do not assume something is not relevant. It's also possible you have old passwords or an oauth token still in use.

Firewall: Access Firewall - it might be the defaulton computer or controlled by an Anti-Virus prgram. Set up Thunderbird program as 'allowed' so nothing gets blocked.

• Confirm Thunderbird is set up as allowed program.

VPN: Check computer for a VPN. Some Anti-Virus products now offer a VPN and I have come across some peopl who did not realise one had been enabled. Switch off VPN (or create split tunnelling and set it up for Thunderbird to use). Gmail does not like VPN as it atempts to hide your IP address, so gmail decides you might be hacker so it auto blocks access.

• Confirm VPN is switched off

Localhost: Do you have anything using the localhost? People who manage websites may typically use eg: Apache Xampp. You need to switch of any program using the localhost whilst setting up gmail. You can enable it again afterwards. I had to switch off Apache Xampp.

• Confirm nothing is using localhost.

In Thunderbird

• Settings > Privacy & Security
• Web Content
• Select 'Accept cookies from sites'
• Click on 'Exceptions' button
• Enter this : https://accounts.google.com
• Click on 'Allow
• Click on 'Save Changes'

   Whilst in that area -

• scroll to Passwords section
• click on 'Saved Passwords'
• If you see any mention of the account you are trying to set up - select the relevant lines and click on 'Remove'
• Click on Close

I would switch off the following as it's still experimental.

*    Settings > General

• Account Hub
• uncheck this checkbox: 'Create accounts in the new Account Hub'

Then create the mail account

• Menu app > New Account > Email
• Enter name
• Enter gmail email address
• Enter password - that means enter the same password you use to access webmail
• Select checkbox to remember password.
• Click on 'Continue'

Thunderbird by default will look for the IMAP server settings. They should be:

• Server name: imap.gmail.com
• Port: 993
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• Username = full gmail email address
• Password is the same one you use to access webmail

Outgoing SMTP:

• Server name: smtp.gmail.com
• Port: 465
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• Username = full gmail email address
• Password is the same one you use to access webmail

• Assuming all is ok click on 'Done'

You should then get the gmail pop up browser type window. It will ask you to confirm you really are you and the then ask if you want to allow Thunderbird access to server.

Then an OAuth token gets created and stored in the same place as all other passwords.

Thank you for your Reply Toad Hall I have not yet solved the problem. Just to clarify a point or two: I have 2 gmail accounts on this PC. They have different Names "John and Barb", and "John Nagy" and identical passwords. I deleted one of these accounts from Thunderbird because it was not downloading incoming messages as described in original post. I am attempting to "Add an Account" from the remaining open account " +New Account" in Account Settings. The "Set Up Your Existing Email Address opens and in the box "Your Full Name" appears the account name for the account still in Thunderbird. I presume I change this to the account Name of the account I am attempting to add ie John and Barb. Is this correct? Working through your points: I have allowed access by Thunderbird through Firewall I do not have a VPN or a local host. I have followed your dot points. Re "Saved Passwords" I noticed that the password for barbnjohn37@gmail, the account I deleted was present so I deleted it, but it returns to the Saved Password box after each unsuccessful attempt to add my account. The password I am using is the one I use to enter Gmail I follow the nominated steps but get the Yellow "Unable to Log" In box, not the Gmail popup Can you offer further advice please?

Thank you for your reply christ 1. I am sending the information requested. Part 2 to follow. As you can see form my other Post, the problem persists.

 Application Basics

   Name: Thunderbird
   Version: 140.7.0esr
   Build ID: 20260109054016
   Distribution ID:

   Update Channel: esr
   User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Thunderbird/140.7.0
   OS: Windows_NT 10.0 26200
   OS Theme:

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
   Fission Windows: 0/0
             Enabled by default
   Remote Processes: 1
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false
   Memory Size (RAM): 15.7 GB
   Disk Space Available: 601 GB

 Mail and News Accounts
   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account4:
     INCOMING: account4, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account7:
     INCOMING: account7, , (imap) imap.mail.me.com:993, SSL, passwordCleartext
     OUTGOING: , smtp.mail.me.com:587, alwaysSTARTTLS, passwordCleartext, true

 Libraries

     Library
     Status
     Expected minimum version
     Version in use
     Path

       RNP (OpenPGP)
       OK
       0.17.1
       0.17.1.MZLA.140.7.0esr.botan
       C:\Program Files\Mozilla Thunderbird\rnp.dll

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

 Calendar Settings

     Birthdays

       Name
       Value

       Name:
       Type: caldav
       Disabled:
       Username:
       URI:
       Refresh Interval:
       Read-only: false
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id3
       iMIP Disabled:
       iMIP Account:
       Organizer Id:
       Force Email Scheduling:
       Popup Alarms Supported:
       Alarms on Invitation Supported:
       Max Alarms Per Event:
       Attachment Supported:
       Max Categories:
       Privacy State Supported:
       Priority Supported:
       Event Supported: true
       Task Supported: false
       Local Time Supported:
       UTC/GMT Supported:
       Auto-Scheduling Supported: true

     Home

       Name
       Value

       Name:
       Type: storage
       Disabled: true
       Username:
       URI:
       Refresh Interval:
       Read-only:
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id3
       iMIP Disabled:
       iMIP Account:
       Organizer 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:

     barbnjohn37@gmail.com

       Name
       Value

       Name:
       Type: caldav
       Disabled: true
       Username:
       URI:
       Refresh Interval:
       Read-only: false
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id3
       iMIP Disabled:
       iMIP Account:
       Organizer Id:
       Force Email Scheduling:
       Popup Alarms Supported:
       Alarms on Invitation Supported:
       Max Alarms Per Event:
       Attachment Supported:
       Max Categories:
       Privacy State Supported:
       Priority Supported:
       Event Supported: true
       Task Supported: true
       Local Time Supported:
       UTC/GMT Supported:
       Auto-Scheduling Supported: false

     Holidays in Australia

       Name
       Value

       Name:
       Type: caldav
       Disabled:
       Username:
       URI:
       Refresh Interval:
       Read-only: false
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id3
       iMIP Disabled:
       iMIP Account:
       Organizer Id:
       Force Email Scheduling:
       Popup Alarms Supported:
       Alarms on Invitation Supported:
       Max Alarms Per Event:
       Attachment Supported:
       Max Categories:
       Privacy State Supported:
       Priority Supported:
       Event Supported: true
       Task Supported: false
       Local Time Supported:
       UTC/GMT Supported:
       Auto-Scheduling Supported: true

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

   GPU: 1

 Add-ons

     Name
     Type
     Version
     Enabled
     Location
     ID

       Amazon.co.uk
       extension
       1.1
       true
       app-builtin
       amazon@search.mozilla.org

       Bing
       extension
       1.0
       true
       app-builtin
       bing@search.mozilla.org

       DuckDuckGo
       extension
       1.0
       true
       app-builtin
       ddg@search.mozilla.org

       Google
       extension
       1.0
       true
       app-builtin
       google@search.mozilla.org

       Wikipedia (en)
       extension
       1.0
       true
       app-builtin
       wikipedia@search.mozilla.org

       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

Here is Part 2 christ1. Security Software

   Type: Name

     Antivirus: Microsoft Defender Antivirus
     Antispyware:
     Firewall: Windows 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 EGL_VENDOR: Google Inc. (Intel) EGL_VERSION: 1.5 (ANGLE 2.1.19739 git hash: 419cd2c3213b) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_ANGLE_windows_ui_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_display_semaphore_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_ANGLE_image_d3d11_texture EGL_ANGLE_create_context_backwards_compatible EGL_KHR_no_config_context EGL_KHR_create_context_no_error EGL_KHR_reusable_sync EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_device_query EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_platform_angle_d3d11on12 EGL_ANGLE_platform_angle_device_id EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_feature_control

     WebGL 1 Driver Renderer: Google Inc. (Intel) -- ANGLE (Intel, Intel(R) UHD Graphics 770 Direct3D11 vs_5_0 ps_5_0, D3D11-32.0.101.7026)
     WebGL 1 Driver Version: OpenGL ES 3.0.0 (ANGLE 2.1.19739 git hash: 419cd2c3213b)
     WebGL 1 Driver Extensions: GL_AMD_performance_monitor GL_ANGLE_base_vertex_base_instance GL_ANGLE_base_vertex_base_instance_shader_builtin GL_ANGLE_client_arrays GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_get_serialized_context_string GL_ANGLE_get_tex_level_parameter GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_memory_size GL_ANGLE_multi_draw GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_lose_context GL_CHROMIUM_sync_query GL_EXT_EGL_image_external_wrap_modes GL_EXT_base_instance GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_clip_control GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_multi_draw_indirect GL_EXT_multisampled_render_to_texture GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_norm16 GL_EXT_tex

Security Software

   Type: Name

     Antivirus: Microsoft Defender Antivirus
     Antispyware:
     Firewall: Windows 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 EGL_VENDOR: Google Inc. (Intel) EGL_VERSION: 1.5 (ANGLE 2.1.19739 git hash: 419cd2c3213b) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_ANGLE_windows_ui_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_display_semaphore_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_ANGLE_image_d3d11_texture EGL_ANGLE_create_context_backwards_compatible EGL_KHR_no_config_context EGL_KHR_create_context_no_error EGL_KHR_reusable_sync EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_device_query EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_platform_angle_d3d11on12 EGL_ANGLE_platform_angle_device_id EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_feature_control

     WebGL 1 Driver Renderer: Google Inc. (Intel) -- ANGLE (Intel, Intel(R) UHD Graphics 770 Direct3D11 vs_5_0 ps_5_0, D3D11-32.0.101.7026)
     WebGL 1 Driver Version: OpenGL ES 3.0.0 (ANGLE 2.1.19739 git hash: 419cd2c3213b)
     WebGL 1 Driver Extensions: GL_AMD_performance_monitor GL_ANGLE_base_vertex_base_instance GL_ANGLE_base_vertex_base_instance_shader_builtin GL_ANGLE_client_arrays GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_get_serialized_context_string GL_ANGLE_get_tex_level_parameter GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_memory_size GL_ANGLE_multi_draw GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_lose_context GL_CHROMIUM_sync_query GL_EXT_EGL_image_external_wrap_modes GL_EXT_base_instance GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_clip_control GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_multi_draw_indirect GL_EXT_multisampled_render_to_texture GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_norm16 GL_EXT_tex