Recently we decided to upgrade our Grails version from 1.3.2 to 1.3.5. Because of our project history we use jetty instead of apache tomcat as our servlet-container, but we thought this shouldn’t be a big deal: for previous upgrades we just had to remove the tomcat-plugin via grails uninstall-plugin within our ide before re-compiling and starting the app.
But this time (at least on my windows-7-machine) we had no possibility to get rid of the tomcat-plugin. Each time we started grails, it tried to use tomcat instead of jetty. The only solution which worked for me was to uninstall the plugin AND to manually delete the physical tomcat folder. The funny thing is, that this was just necessary on my windows-machine: a colleague had no problems on his Mac.
Maybe I should mention that we “upgraded” our grails version within IntelliJ 9.0.3 and not directly via the grails-console-commands. We didn’t do any more research on this topic, so we don’t know if this is an IntelliJ or a Grails issue. But maybe this blog-entry can help others having the same problems.
REWOO Blog 
I cannot reproduce this issue on my machine. Please, try to uninstall the tomcat-plugin via the grails-console-commands to find out whose issue is it.
Regards,
IntelliJ developer.
I’ve done the following steps to upgrade within the command-box:
grails upgrade (message: “Plugin tomcat-1.3.5 installed”)
grails uninstall-plugin tomcat 1.3.5 (Afterwards: a call to grails list-plugins shows that tomcat isn’t still present)
grails run-app
Everything works fine, if we upgrade this way.