Is there a bug in File Manager?

[Ralf Mardorf]

On Tue, 2020-04-14 at 13:54 +0800, Turritopsis Dohrnii Teo En Ming
wrote:
> There was an incident when I was trying to do backup. I tried to copy 
> files and folders from my home directory to portable external harddrives 
> but noticed many files and folders were not copied over.
> 
> Is there a bug in File Manager?
> 
> Could you recommend a reliable way to backup files and folders (no 
> skipping of files and folders)?

In nautilus' burger menu "Show Hidden Files" must be checked.
However, if the issue already appeared for dragged and dropped or by the
right click menu's "Copy to..." selected items, IOW if it shouldn't be
related to hidden items, then

- are really all desired items selected?
- do some items in $HOME exceed the size limit of the external drives'
  file system?
- do the file names contain only letters that are acceptable for the
  external drives' file system?
- do all items have the same permissions? IOW could it be that
  permission of some items and/or the target drive are an issue?
- etc., pp. ...

Are there any messages? Progress bars with text? Warnings? Errors?

How about command line? For example

sudo cp -ai /home /mount/point/target/; echo $?

In the future, could you please refrain from adding the obligatory
signatures with your usual scattered thoughts, that are larger than your
actual request/s?