Why is password requested repetitively to mount encrypted USB drive?

I have a USB drive, encrypted with LUKS [cryptsetup](https://gitlab.com/cryptsetup/cryptsetup) , that I use for regular backups. When I plug in the drive, I am prompted for a password, just as expected. But then the drive gets mounted, an icon appears on my desktop, and a second password dialogue is shown. The message in the dialogue – “A passphrase is needed to access …” is wrong. I can ignore the second dialogue, or cancel it, and I am able to access the drive. See the screen-shot, which shows the drive icon (unlocked), files on it in Nemo, and the second password dialogue. It gets weirder: if I enter my password again, it is rejected and the dialogue reappears. This seems to happen infinitely, until I Cancel the dialogue. Is this a bug, or am I doing something wrong? Here is the lsblk output (sda is the USB drive): NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS sda 8:0 1 233G 0 disk └─sda1 8:1 1 233G 0 part └─luks-4c8f9d1b-f967-4257-91d5-c32db662e482 252:0 0 233G 0 crypt /media/ME/BackupRed nvme0n1 259:0 0 931.5G 0 disk ├─nvme0n1p1 259:1 0 512M 0 part /boot/efi └─nvme0n1p2 259:2 0 931G 0 part / I am using Linux Mint 22.1 Cinnamon. There are similar questions but they refer to boot problems. e.g. https://askubuntu.com/questions/1106136/prompted-for-luks-password-twice-on-boot-despite-separate-unencrypted-boot-part . **Edit - Answers to early comments.** I don’t have KDE, it’s not even in the Mint distro. I tried running ps -fu ME at various stages: • No new processes when USB plugged in • No new processes when first dialogue cancelled • No new processes when first dialogue completed All of which leads me to assume the dialogues are part of Cinnamon, and not a separate process. ** Edit - Answers to @waltinator ** No output at all from sudo journalctl --follow |tail -f. It was started before the drive was plugged in, and left running through both dialogues. Here are my notes from when the drive was encrypted. It was brand-new so had nothing to save. > To use the GUI: Launch Disks to get access to the encryption utility. > Plug in your memory stick and look for it in the list of available > disks. Create a temporary folder and copy out all of the files you > have on the stick. Next, you choose to format the external drive, > specifying the encryption option. Remember, this action will mean > that you will only be able to access the files on Linux computers > that also have cryptsetup installed. If you don’t want to encrypt the > entire memory stick, partition it first. This action can also be > performed in the Disks utility. > > You specify a password when the > Format procedure launches. The formatting process offers you the > option to not overwrite existing data. However, this doesn’t work and > you will lose all of your files on the memory stick during the > formatting process. That’s why you need to copy them over to a > temporary folder before you start the encryption process. Once the > formatting finishes, copy your files back over. > > A drive that has been > protected by encryption is flagged in the Disks display by a padlock > icon. Henceforth, when you click on that drive to access it, a popup > window will appear to prompt you for the password. Options in the > popup specify whether the computer should store the password for > future access, whether it should forget the password immediately, or > whether it should forget the password once the USB stick is removed > from the computer.