Why do I get the error, "org.eclipse.core.runtime.CoreException: Plugin was unable to instantiate class...", when attempting to check-out from StarTeam Eclipse?
This error is caused by having more than one version of StarTeam Eclipse installed and enabled on Eclipse. This can come about after upgrading / installing a later version of the Eclipse plugin.
You must disable all versions not being used, leaving only one active and enabled version. You normally will want to disable all earlier versions of the Eclipse plugin.
To disable specific versions of the plugin, do the following;