Problem with backing up docker mysql

I am trying to backup a Mysql docker container from another machine and i get the following error:

InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: File /var/lib/mysql/ib_logfile0: ‘open’ returned OS error 71. Cannot continue operation
InnoDB: Cannot continue operation.

It looks like a permission error but i qm pretty confident that everything is setup correctly. The data directory of the container is mapped to a folder on my pc that belongs to “mysql” user. Also inside the container all the configuration files and the data belong to mysql. I read about this bug https://bugs.launchpad.net/percona-xtrabackup/+bug/1526467 which is exactly my case, but upgrading to xtrabackup 2.4 did not help…

Am i missing something?