When trying to get reference images for more than about 10 screenshots when using the grahics playmode test framework (included in the Scriptable Render Pipeline project https://github.com/Unity-Technologies/ScriptableRenderPipeline) an error prevents all the screenshots being written into the test results.

Can not send network message. Receiver can not keep up with the amount of data sent
UnityEngine.PlayerConnectionInternal:SendMessage(String, Byte[], Int32)
UnityEngine.PlayerConnectionInternal:UnityEngine.IPlayerEditorConnectionNative.SendMessage(Guid, Byte[], Int32)
UnityEngine.Networking.PlayerConnection.PlayerConnection:Send(Guid, Byte[])
UnityEngine.TestTools.TestRunner.Callbacks.<SendDataRoutine>c__Iterator0:MoveNext() (at C:\buildslave\unity\build\Extensions\TestRunner\UnityEngine.TestRunner\TestRunner\Callbacks\RemoteTestResultSender.cs:129)
UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)

[C:\buildslave\unity\build\Runtime/Network/PlayerCommunicator/GeneralConnection.cpp line 452]
(Filename: C:/buildslave/unity/build/Extensions/TestRunner/UnityEngine.TestRunner/TestRunner/Callbacks/RemoteTestResultSender.cs Line: 129)

Appears to be a problem when the player sends the results back to the editor at the end of a test run.

I didn't mark this as a Graphics Playmode Test package issue as although this package can reproduce the issue it doesn't seem specific to it but more an issue with sending a large amount of data back to the editor for the test results.

Relevant Slack thread for this https://unity.slack.com/archives/C0JHA6J4C/p1539116537000100