Unable to decrypt file copied from USB thumb drive.

[Chris Taylor]

Hello Group,

I am developing a backup process for personal files, on USB thumb 
drive.  I tar and zip my files (30GB) then encrypt them with:

gpg --no-symkey-cache --symmetric --cipher-algo AES256 my-backup.tar.gz

I copy my-backup.tar.gz.gpg to my USB thumb drive.  I am using Ubuntu so 
the USB drive is formatted to Ext4.

I try to decrypt with:

gpg --output my-backup.tar.gz --decrypt my-backup.tar.gz.gpg

and get the following error:

gpg: AES256 encrypted data
gpg: encrypted with 1 passphrase
gpg: block_filter 0x0000556d112aa1e0: read error (size=13328,a->size=13328)
gpg: WARNING: encrypted message has been manipulated!
gpg: block_filter: pending bytes!

I have gpg version 2.2.19, libgcrypt 1.8.5.  Without encryption this 
process has worked perfectly well many times.

Any advice greatly appreciated.

Chris.