Issue Failed to connect to target Plesk server by Plesk API: <urlopen error [SSL: SSLV3_ALERT_HANDSHAKE_FAILURE] sslv3 alert handshake failure (_ssl.c:590)

[Robert Spragg]

We have a dying server (running Plesk Onyx 17.8.11 #82) and a new server to replace it running Obsidian 18.0.21.
Trying to migrate from the old server to the new one produces the above error.
I have Googled and tried a couple of suggestions but none of them have fixed the issue...and there isn't much info relating DIRECTLY to this exact error.
I get the same error if i try and migrate from another (working) Obsidian 18.0.21 server we have. If i try and migrate from the old Onyx server to this other working Obsidian server then it works fine.
Does anyone have any ideas as to what this could be please ?

 

[Robert Spragg]

Update : We have now succeeded in upgrading both of the 18.0.21 servers to 18.0.24 (the sources at our provider OVH were faulty and not allowing update beyond 18.0.21).
We have also succeeded in updating the Onxy server to Obsidian 18.0.24. We still cannot migrate anything from the old server to either of the two new servers - same error as at the top of this thread.