I have this problem as well. It appears to have started with the latest version of Thunderbird that I installed (78.0.1), 32-bit. I'm running Windows 10 Pro.

Not only do have the same problem and failed workarounds as Skyline57, there also is a related problem with writing emails. If I start a new email and paste an image into the body that I have copied from the web, the image doesn't display. Instead, there is a strange, re sizable symbol instead of the image. This symbol looks like a coffee cup over a small sawtooth shape (it probably has some technical name) and is shown below. Strangely, if I copy an image from the web and paste it into Irfanview-64 (or similar image editors), copy it within that open program, and then paste it into the new email body, the image will show just fine.

Another error which may be related - I cannot reach the addon site addons.thunderbird.net, within Thunderbird. If I go to the Addons Manager and enter any text in the Addons search box, a tab opens with the message: "Secure connection failed

An error occurred during a connection to addons.thunderbird.net. Peer’s certificate has an invalid signature. Error code: <a id="errorCode" title="SEC_ERROR_BAD_SIGNATURE">SEC_ERROR_BAD_SIGNATURE</a>

   The page you are trying to view can not be shown because the authenticity of the received data could not be verified.
   Please contact the website owners to inform them of this problem"

I can reach addons.thunderbird.net via the Firefox or any other browser. I suspect that the same error that will not allow Thunderbird to reach addons.thunderbird.net is blocking remote images.

Anyone have any ideas?

Disable scanning of secure connections in your anti virus will probably cure all of your issues Skyline.

You could test my theory in Windows safe mode with Networking.

Disable scanning of secure connections in your anti virus will probably cure all of your issues Skyline. You could test my theory in Windows safe mode with Networking.

Thanks for the suggestion. Unfortunately it didn't work. I set Eset to exclude Thunderbird from protocol scanning - no change. Disabled all protocol scanning - no change. Paused Eset - no change. The behavior continues in Windows safe mode with Networking. Any more ideas?

I think I have solved the problem by upgrading from version 60.9.1 to version 68.0. I only lost one add-on (Highlighter), and images seem to display correctly in the more recent version.

nadpete When you copy an image from the web you are not just copying the image, you are also copying a load of hidden remote content, so the image will not display. The symbol that looks like a coffee cup over a small sawtooth shape means a broken image and is used to indicate an image was in that location but for some reason cannot be shown. The most common reason being it contains remote content. Once you open image with irfanview and resave it will convert into a simple plain image stored on your computer, so that will insert ok.

@Toad-Hall I get what you are saying, but the issue (which affected all emails in all accounts) didn't occur when I tried Outlook and Microsoft Mail, which led me to try upgrading TB. So there is some issue with version 60.9.1 that isn't present in version 68.

@Toad-Hall I get what you are saying, but the issue (which affected all emails in all accounts) didn't occur when I tried Outlook and Microsoft Mail, which led me to try upgrading TB. So there is some issue with version 60.9.1 that isn't present in version 68.

Quite possible. You will also probably see other display bugs fixed in 78. It is an ongoing process of improvement that is never back-ported to old versions once a new version is released. There are still issues with how Thunderbird interprets some remote images. Often the issue is due to the remote "image" not actually being an image and therefore unlikely to ever be resolved. It is common on some sites to put an image on the screen using a script. Thunderbird does not do embedded scrips for security reasons. Scripts are how you suddenly get ransomware when you open an email.

An example if a script displaying an image is what facebook does when you look in an album, you see pictures, but you don't actually get a link to the pictures, the links are to facebook scripts that load the while "face book experience" so if you copy the image to an email you are not actually placing a link to an image. If you right click in facebook at the point of viewing the image there is a menu in Firefox that offered to "view image" and now your getting to a point where the image linked is actually an image file.