I get that error in NeoLoad when i test the connection. This is a subset of the error stack trace:
org.eclipse.jgit.api.errors.TransportException: ssh://git@mygitserver.com:22/neoload/neoload.git: invalid privatekey: [B@115b4563
at org.eclipse.jgit.api.LsRemoteCommand.execute(LsRemoteCommand.java:222)
at org.eclipse.jgit.api.LsRemoteCommand.call(LsRemoteCommand.java:161)
at com.neotys.nl.k.a.a.r.c(r.java:254)
at com.neotys.nl.k.a.a.r.b(r.java:144)
at com.neotys.nl.k.a.a.r.a(r.java:140)
at com.neotys.nl.k.a.p.a(p.java:34)
at com.neotys.nl.gui.h.bj.z(bj.java:805)
at com.neotys.nl.gui.h.bj.access$000(bj.java:56)
at com.neotys.nl.gui.h.aS.run(aS.java:158)
If i use the same key pair with git bash i'm able to clone my repository so i know that they are working.
NeoLoad uses Jsch for the SSH interaction with git. The key point is that You need to generate a key pair in a PEM format.
This error usually occurs when the header format of the private key is not RSA but something else like for example ed25519.
You may have to generate a new keypair using the -m PEM option like this: ssh-keygen -t rsa -m PEM so it can be used by Jsch.