Steps to reproduce:

1. Open Unity on Windows (DX11 mode);
2. Create new project or open attached one;
3. Go to Build Settings (File -> Build Settings);
4. Switch platform to PC, Mac & Linux Standalone;
5. Check 'Development Build' and 'Autoconnect Profiler' options;
6. Build&Run the project;
7. When scene loads switch to opened Profiler window;
8. Choose Add Profiler -> GPU;
9. Observe Editor console.

Actual result:
Weird uninformative errors are spammed to the console when adding GPU profiler:

"!query->pending"

See attached screenshot and gif video.

Same errors are thrown in Editor when exiting Play with GPU profiler enabled after having received the following error firstly in Standalone build.

Regression introduced somewhere between 5.3.0a3 and 5.3.0b6.

Expected result:
"!query->pending" errors should not be displayed when adding GPU profiler.

Notes:
- Reproduces in 5.4.0b4, 5.3.0f3 and 5.2.0f3, 5.3.0b6;
- Doesn't repro in 5.3.0a3;
- Doesn't repro in OSX 10.11.3 and Windows in GLCore mode. In this case message telling that graphics driver doesn't support GPU profiling is displayed;
- The issue may be GPU hardware-related (getting repro on GeForce 640M).