Ran into this issue yesterday. Had just upgraded my R9 390 from 4.9.1 to 4.9.4, updated Afterburner for diagnostics. Went on a road trip with my Dad and, on my way around doing Power Play resupplies, hit this lock problem when trying to fly to the station 2200Ls away from the sun. I first started by making sure the GPU hadn't come loose, then tried a lower power profile (-50%). No change at all. Soon as I Super Cruise, it freezes and the error pops up. Decided to roll bag my drivers to the last version I knew worked. All's golden so far, no more error.
As a programmers note, the buffer lock isnt part of the problem, it's a symptom. The game needs to lock the buffer to draw to it. If this stays locked for too long, it will error out. My case was a bad driver. Bad files, hard to read files, bad networking can all bottleneck the process. The more strain you put on the device, the more likely it is to occur. If this happens in any other 3D program, suspect drivers. If this only happens in Elite, suspect storage. If Elite is installed on an SSD other than the OS and significant software, suspect power. If power changes make no difference, you may be plugged into the wrong GPU, or your GPU is failing you. Look into reapplying thermal paste (cracks won't show heat problems, but may cause performance problems) or try another GPU if you have one lying around. More solutions may exist, but this should help those who run across it in the near future.
