I connect via tns and tnsnames.ora file provided by our it department. When I connect with a different application there isn't any problem. So I do not think its a spelling mistake or something like that.
I found one posting suggesting it might be related to specific jar files (http://www.christoph-jahn.com/?p=1074) ' but it doesn't mention any details,
I installed SqlDeveloper 3.1, JDK 1.6 - but to no avail.
Still using TNS connection type but ....
... when I connect via "connection id" and not "network alias" I can connect to the database in question. So, that's ok even so it is not as convenient as to choose a network alias of the drop down list.
Been strugling with the same error for a while. SQL Developer worked just fine in a Windows VM but not in my Mac OS X.
Didn't matter if i was connected by cable or wireless , was using IP adress and not hostname, tried several other fixes with no luck.
Today i exported the connections from the developer in the VM and imported them on to the v4.0.0 developer on Mac OS.
Worked ... go figure