"OSStatus Error 5" while restoring HD to external SSD with Disk Utility in Recovery mode

I recently bought a Sandisk SSD (2TB) in order to restore a bootable backup of my MacBook pro (mid-2012) running on macOS Mojave (10.14.2).

First think I have done is connected the external SSD in a casing with USB. With Disk Utility I erased the external drive to format in AFPS.

Second, I performed an First Aid to my internal Macintosh HD (750GB). This was completed successfully without any issues.

By know I thought everything was set to restore a bootable backup from the Macintosh HD to SSD, so I restarted my MacBook Pro in recovery mode by holding Command+R after the chime. Then I selected the SSD as destination and Macintosh HD as source for the restore. Everything seemed alright till now.

Then after 134GB of restoring it gives a message that the restore process has failed and only option is to press continue. In the details there is the following error:

"could not restore - input/output error

The restoring process could not be completed. (OSStatus error 5.)" *translated from dutch.

Does anyone has the same experience? And how should I solve this issue?

Thanks a lot!