Arman,
This error is an error from the Application Server to the Eclipse debugger letting it know “Hey, I tried to hotsync that code you gave me, and I couldn’t, sorry.”, so you have two choices at this point:
1) You can touch or update the web.xml file to cause weblogic to reload the context
OR
2) You can simply restart WebLogic
You don’t need to restart Eclipse, that’s not the problem. Infact this dialog is just a notification that WILL happen with any app server, the Java spec for hot code replacement is very limited, during development it is very liekly you will try and hot sync code that cannot be synced and you will get this error message, then follow the two options I gave above. It’s just part of development, I get this too when I work on Tomcat and JBoss.