Jenkins: signature verification failed in update site 'default' (show details)

Question

I have installed Jenkins on Amazon EC2 instance and I am trying to get an updated list of available plugins.
When I go to Manage Plugins --> Advanced --> Check now(at the bottom), I get an error as below:

signature verification failed in update site 'default' (show details)

Answer 1

Please see https://issues.jenkins-ci.org/browse/JENKINS-31089 which is relevant but should be fixed on the latest builds.

For me the fix was a little different. The java.security file had

jdk.certpath.disabledAlgorithms=MD2, MD5, RSA keySize < 1024

I removed MD5 from this list to make it

jdk.certpath.disabledAlgorithms=MD2, RSA keySize < 1024

This resolved the issue for me.