I'm getting an error trying to get into IPD either logging into our test instance or working offline. The message says "An error has occurred. See the log fie". The log is very lengthy, but the start of it says:
eclipse.buildId=unknown java.version=1.6.0_20 java.vendor=Sun Microsystems Inc. BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_US Command-line arguments: -os win32 -ws win32 -arch x86
!ENTRY org.eclipse.osgi 4 0 2016-06-13 16:11:58.209 !MESSAGE Application error !STACK 1 java.lang.StackOverflowError
IPD was working fine for me earlier in the morning. I hadn't changed anything so I'm not sure what happened. There was an issue with IPA that we have on prem. Our administration rebooted the server, restarted the grid and ibm websphere. He can telnet into the server via the port I have configured in my connections. So I'm not sure if there's something going on with IPD or if there's something else the admin needs to do.
Did you first uninstall the Designer through Control Panel?