Fixing Eclipse Tomcat WTP Startup Issues
The Eclipse WTP tools seem to have problems when the JDK in use changes. There does not appear to be any UI feature that allows a user to tell the WTP server which JDK to use, causing it to fail to start with various error messages. Thankful to this blog post, I have found a fix that has reliably worked. I keep referring to the page, so thought I'd regurgitate it here...
Solution : delete the [WORKSPACE_NAME]\.metadata\.plugins\org.eclipse.debug.core\.launches\[WTP_SERVER_NAME].launch file