No apparent support for spaces in subvolume declaration about btrbk HOT 4 CLOSED

Yes, this is on puropse. From the man-page:

Note that btrfs is very picky on file names (mainly for security reasons), only the characters [0-9] [a-z] [A-Z] and "._+-@" are allowed.

If you are brave, change the according line in btrbk:

110: my $file_match = qr/[0-9a-zA-Z_@\+\-\.\/]+/;

You might run into trouble when allowing whitespace characters. This is always a pain to handle correctly with all those external tools needing special care on escaping special characters. This will probably never be implemented in btrbk.

As a general rule of thumb, I'd NEVER use special characters on the file/folder names, sooner or later there's a tool that does not handle it correctly. Use underscore _ character instead of spaces.

from btrbk.

As a workaround, you could make a symlink to those subvolumes, and specify the symlink in btrbk.conf.

from btrbk.

Oh okay.
I kept spaces in certain folders (namely those mentioned above) because they came like that as a default. I didn't think much of it.
I went ahead and symlinked both to another location and it works perfectly, thanks.

from btrbk.

This is all well-documented in btrbk-0.21.0, closing issue

from btrbk.