Failed to instantiate class hudson.plugins.copyartifact.CopyArtifact

I seem to be unable to select a project to copy an artifact from via the job config. Any time I try to and press save I get the following error msg:

Exception: java.lang.RuntimeException: Failed to instantiate class hudson.plugins.copyartifact.CopyArtifact from {"projectName":"Moho","":"0","selector":

{"stapler-class":"hudson.plugins.copyartifact.StatusBuildSelector","stableOnly":false}

,"filter":"*//mysql.provisioning.sql-*.tar.gz","target":"target/artifacts/","parameters":"","flatten":true,"optional":false,"stapler-class":"hudson.plugins.copyartifact.CopyArtifact","kind":"hudson.plugins.copyartifact.CopyArtifact"}
Stacktrace:

Full logs: https://gist.github.com/johntdyer/4ecd0135fad5586c637f

This is version 1.26