Log:
Minecraft process ID: 18368

Using onesix launcher.

[19:01:03] [main/INFO]: Building optimized datafixer
Process crashed with exitcode -1073741819 (0xffffffffc0000005).
Below is an analysis of the exit code. THIS MAY BE INCORRECT AND SHOULD BE TAKEN WITH A GRAIN OF SALT!
System exit code name: STATUS_ACCESS_VIOLATION
System exit code description: The instruction at 0x%p referenced memory at 0x%p. The operation %s could not be performed in memory.

Please note that usually neither the exit code, nor its description are enough to diagnose issues!
Always upload the entire log and not just the exit code.