I am not a python developer so when I got to errors in the section that is actually streaming the files I decided to stop and just finish 'making' python2.7 on the servers that I need to get the VMs off and that has worked for me.

It doesn't seem like it should be a huge amount of work left to upgrade the script to python3 but probably not something I have the skills or time for right now.

Thanks for sharing your efforts here. What have you ended up doing @josef1909

(Pdb) n
> /root/xen2xcpng3-V1.py(871)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) w
  /usr/lib/python3.9/bdb.py(580)run()
-> exec(cmd, globals, locals)
  <string>(1)<module>()
> /root/xen2xcpng3-V1.py(871)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) n
VM Details:
Name: JUSTANOTHERNAME
Type: Paravirtualised
VCPUS: 4
Memory(bytes): 2147483648
ACPI: true
APIC: true
PAE: true
NX: false
Viridian: true
Disk xvda(Bootable): /dev/vgxen/JUSTANOTHERNAME
Connecting to target xxx.xxx.xxx.157

Processing disk /dev/vgxen/JUSTANOTHERNAME(21474836480 bytes)
TypeError: initial_value must be str or None, not bytes
> /root/xen2xcpng3-V1.py(871)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) w
  /usr/lib/python3.9/bdb.py(580)run()
-> exec(cmd, globals, locals)
  <string>(1)<module>()
> /root/xen2xcpng3-V1.py(871)<module>()
-> machine.save_as(server=options.server, username=options.username,
  /root/xen2xcpng3-V1.py(617)save_as()
-> string = io.StringIO(input_buffer)
(Pdb) n
--Return--
> /root/xen2xcpng3-V1.py(871)<module>()->None
-> machine.save_as(server=options.server, username=options.username,
(Pdb) w
  /usr/lib/python3.9/bdb.py(580)run()
-> exec(cmd, globals, locals)
  <string>(1)<module>()->None
> /root/xen2xcpng3-V1.py(871)<module>()->None
-> machine.save_as(server=options.server, username=options.username,
(Pdb) n
TypeError: initial_value must be str or None, not bytes
> <string>(1)<module>()->None
(Pdb) w
  /usr/lib/python3.9/bdb.py(580)run()
-> exec(cmd, globals, locals)
> <string>(1)<module>()->None
  /root/xen2xcpng3-V1.py(871)<module>()->None
-> machine.save_as(server=options.server, username=options.username,
  /root/xen2xcpng3-V1.py(617)save_as()
-> string = io.StringIO(input_buffer)
(Pdb) n
--Return--
> <string>(1)<module>()->None
(Pdb) w
  /usr/lib/python3.9/bdb.py(580)run()
-> exec(cmd, globals, locals)
> <string>(1)<module>()->None
(Pdb) n
Traceback (most recent call last):
  File "/usr/lib/python3.9/pdb.py", line 1723, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib/python3.9/pdb.py", line 1583, in _runscript
    self.run(statement)
  File "/usr/lib/python3.9/bdb.py", line 580, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/root/xen2xcpng3-V1.py", line 871, in <module>
    machine.save_as(server=options.server, username=options.username,
  File "/root/xen2xcpng3-V1.py", line 617, in save_as
    string = io.StringIO(input_buffer)
TypeError: initial_value must be str or None, not bytes
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /root/xen2xcpng3-V1.py(617)save_as()
-> string = io.StringIO(input_buffer)
(Pdb) q
Post mortem debugger finished. The /root/xen2xcpng3-V1.py will be restarted
> /root/xen2xcpng3-V1.py(13)<module>()

In the meantime, I made some Tests and will provide the last lines from the debugging.

> /root/xen2xcpng3-V1.py(839)<module>()
-> if options.filename:
(Pdb) n
> /root/xen2xcpng3-V1.py(842)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) n
> /root/xen2xcpng3-V1.py(843)<module>()
-> password=options.password, ssl= not options.nossl,  sparse=options.sparse, sftp=options.sftp)
(Pdb) n
> /root/xen2xcpng3-V1.py(842)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) n
VM Details:
Name: JUSTANOTHERNAME
Type: Paravirtualised
VCPUS: 4
Memory(bytes): 2147483648
ACPI: true
APIC: true
PAE: true
NX: false
Viridian: true
Disk xvda(Bootable): /dev/vgxen/JUSTANOTHERNAME
Connecting to target XXX.XXX.XXX.157

Processing disk /dev/vgxen/JUSTANOTHERNAME(21474836480 bytes)
TypeError: initial_value must be str or None, not bytes
> /root/xen2xcpng3-V1.py(842)<module>()
-> machine.save_as(server=options.server, username=options.username,
(Pdb) 

We are pretty busy here (at Vates) about 8.2.1 new ISO and 8.3 release. We'll be happy that anyone around in the community is able to assist!

Processing disk /dev/vgxen/justanothername(21474836480 bytes)
Internal Error. Possible problem: Please make sure you have enough space on your default SR

While this is an issue which is announced on the link you send, I check via xoa and xcp-ng center. We have set a default SR. may I ask your help to proceed?

Take a look at https://docs.xcp-ng.org/installation/migrate-to-xcp-ng/#-from-xen-on-linux