Comment 1 for bug 1787242

I have done a bit more research:

1. This doesn't happen with PcManFM. The default Lubuntu file manager will install quite happily onto U.Mate and both USB HDD's and sticks will mount and unmount without problems.

2. I have noticed that if using a USB stick that Caja holds up if selecting 'eject'. It only fails if selecting 'safely remove drive'. The latter is of course the only option with external HDD.

3. I would caution anyone trying to replicate this error not to have important data on the drive as it does seem to cause damage the external drive file system. (Gnome Disks does repair this though).

4. Synaptic lists pcmanfm as using GVFS for removable media, which I think is the same as Caja.

5. Of note, I have had this problem for quite a while, certainly since 18.04 but not sure about before that. I originally thought it was the drive, not the software .... I have also carried out re-installs of Caja, gvfs and other components too.

I now think this problem centres on the 'safely remove drive' button function of Caja and probably an upstream fix will be needed.

Hope someone familiar with Caja's inner workings can fix this.