Hello,
I realize that this thread has appeared in the past, but I am ringing a huge bell at the moment, given the gravity of the situation.
When I opened my project today, I would receive a few of these warnings in my console, all of a sudden. After restarting the editor and looking for answers on these forums, no one had come up with a proper solution, so I decided to ignore them.
After I started coding, I turned back on the editor and the messages will update on every frame. They are literally thousands already and, upon clearing the console, they won’t stop appearing. It is as if you have a Debug.Log on an Update() function which, if cleared, will not stop displaying the messages.
The message I receive, as mentioned on the title, is “Sending Message Header Failed”. Unfortunately, double clicking it won’t tell me where this comes from, but why would it, given that it originates from the Editor (the messages have bombarded the console while I am either in Play Mode or not).
The actual problem is that the editor has started lagging and I am startled as to why this issue emerged all of a sudden today, without having performed an update.
I tried disabling features in the scene I had not used in the past (e.g. SpeedTree modules), in order to gradually limit my search for the problem, but to no avail.
Something is causing the editor to behave unnaturally and it literally won’t stop.
I sincerely do not know what might be causing it and it already is a big project to send it out for inspection (plus the NDA restrictions) or to tell you how you would reproduce it, given that it occurred abruptly.
Any help will be appreciated.
Regards
P.S. I do not have any custom inspector scripts; I am running Unity version 5.3.4f1 Personal.