Crash happened only twice.

1. Run Standalone as Host.
2. Run in Editor as Client.
3. Run Profiler - Set Active profiler as OSXPlayer).
4. Close Standalone.
5. Return to Unity.
6. Press on Profiler - Select OSXPlayer in Active Profiler.

Actual result: Unity crashes or throws errors:

Socket: connect failed, error: Connection refused(61)
UnityEditorInternal.ProfilerDriver:set_connectedProfiler(Int32)
UnityEditor.AttachProfilerUI:SelectProfilerClick(Object, String[], Int32)
connect failed
UnityEditorInternal.ProfilerDriver:set_connectedProfiler(Int32)
UnityEditor.AttachProfilerUI:SelectProfilerClick(Object, String[], Int32)
Failed to connect to player ip: 172.31.26.46, port: 55147
UnityEditorInternal.ProfilerDriver:set_connectedProfiler(Int32)
UnityEditor.AttachProfilerUI:SelectProfilerClick(Object, String[], Int32)

Expected result: Unity does not crash.

Reproduced on 5.5.0b2.
Does not reproduced in 5.4.0f1.