How are you entering a command and asking that the messages be deleted?

I selected them, and then right clicked on them and hit the Garbage can icon. I also tried dragging the selected files to the Trash folder.

How many messages are you trying to delete or move at once? Do these operations work on a single message?

What is your anti-virus software?

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.

Thanks for your replies. I can delete messages one by one. Sometimes I can delete two at a time. But I cannot move or delete 3 or more selected messages.

Now I am getting this message: The folder 'Inbox on constans@sfu.ca' could not be compacted because writing to folder failed. Verify that you have enough disk space, and that you have write privileges to the file system, then try again

I have plenty of disk space - 124 GB free out of 222GB.

any idea what could be causing this?

Seems to confirm christ1’s diagnosis. Response to their message?

I re-booted in Safe mode. Still could not move or delete files.

In Windows safe mode, would you please also try Thunderbird’s troubleshooting mode? See the help menu.

I will try it, thanks. Also am getting this message: The account constans@sfu.ca is being processed. Please wait until processing is complete to get messages.

Do you have more than one account that use the same inbox?

No, only one mail address.

Here is where I am now: I am using Safe mode and using Thunderbird Troubleshooting Mode. I cannot select any file in my Inbox, although I can see them in the Index. The program endlessly says that it is moving files to Trash, and I get a flickering blue line (progress line?) on the bottom right. I have closed the program and restarted it. I also have completely shut down the computer and restarted it. But when I open the program, it still says that it is moving files to Trash.

Can I re-install Thunderbird without losing all my messages? Thanks for any advice.

You can re-install without affecting your messages. Back up your profile first anyway.

Can you delete and move messages in webmail?

Yes, if you mean on the server? In addition to the misbehaving laptop (PC Lenovo) I also have Thunderbird installed separately on my home desktop (Mac Mini) and my computer at work (Desktop PC). It is working fine on all except the laptop Lenovo. Tomorrow I will try re-installing Thunderbird on that machine and see if it helps. Thanks for your help.

This is left field, but check the integrity of the disk using the chkdsk utility. without an antivirus to cause contention there is a something of a lack of reasons for there to be issues writing to a folder.

I would also suggest this https://support.mozilla.org/en-US/kb/rebuilding-global-database when the global database becomes corrupted processes tend to hang (long running things like the activity manager sitting all day on determining which messages to index, and the folder is being processed for extended periods. The location of mail is not really known to the search system in these circumstances an global searches routinely turn up messages that do not display when selected. It costs nothing and can be quite helpful.

Despite there being a popular process of reinstalling be aware it rarely fixes anything that does not relate to system integration. Thunderbird does not store user settings in the registry as Microsoft software does and a reinstall therefore fixes basically nothing. It may fix issues around MAPI and system notification about not having a mail application installed. It is most unlikely to fix this.

Some issues that might cause this sort of issue beyond what I already suggested , or including them, are; 1. Disk corruption. 2. Disk sync to another location. More common these days where folks change the default locations to places synced to things like Google drive in a vain attempt to synchronize their profile across devices.. 3. The profile is stored on a networked location like a local server or NAS. 4. Streaming backups.

Hi Matt. Thanks for your response. I ran the disk check and it came up no errors. Then I deleted the global-messages-db.sqlite file in my profile and restarted Thunderbird. I was able to download new mail, but when I tried to sort it by correspondent, the program stalled again and gave the message "Loading message" with constantly running blue bar in the lower right hand corner. I tried to move the top 3 messages into a folder , and when I right clicked on the selected messages one of the choices was "move to cat again". That was the folder that I tried to move those messages to before I deleted the global-messages-db.sqlite file from my profile. So there is still something in there that is screwing things up. However I notice now that the new global-messages-db.sqlite file is only half as big as the old one. So I'll try it again and see if there is any improvement. Thanks.

An important piece missing here is what is your version number?

A reinstall isn't going to help you nor global-messages-db.sqlite - this wouldn't cause message selection nor moving to fail.

If all of this selection is happening in the Inbox, and it is an imap account

• right click Inbox > properties > Synchronization > uncheck "Select this folder".
• Find your profile directory and then the Inbox file for the account.
• Shut down Thunderbird
• Delete Inbox and Inbox.msf.
• Start Thunderbird.

Hi Wayne. The version of Thunderbird I have on this machine is 140.2.0esr (32 bit). It is not an imap account - it is a popserver account. I do not synchronize it between my machines. And I have nothing in the cloud.

Naive question - has there been a recent update to Thunderbird that could be causing this issue? Could I revert to an earlier version? I saved my profile and uninstalled and clean re-installed Thunderbird. But when I imported my profile, all the same problems came back. So it must be a problem with my profile? Does anyone know what that could be? BTW my global-messages-db.sqlite file is huge - over 200,000 KB. Is this normal? I have tried deleting it and starting over. When I first log on that folder is much smaller, but as soon as I try to sort the Inbox, it returns to the same huge size.

     I don't know if any of this is relevant, but I'm just throwing it out there.  Thanks again.