An unexpected issue occurred and the game has crashed

Please do not mark unreleased versions as affected.
You don't have access to them yet.

Is this MC-12949?

Picked up _JAVA_OPTIONS: -Xmx256M

-Xms256M is not enough to run Minecraft. See MC-12949 to increase memory.

Proposed change to increase memory was unsuccessful.  Still getting the same issue.  Increased the memory to both 4G and 6G, still crashes in version 1.13 and higher.

Please attach the crash report found in [.minecraft/crash-reports|http://hopper.minecraft.net/help/guides/finding-minecraft-data-folder/].

-Xmx1G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M

I don't see the second Xmx flag -Xmx256M

JVM Flags: 10 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx6G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M -Xmx256M

I thought that was your problem, but apparently not. Also, you seem to be having the same issue as MC-135697.

Does MC-74465 fix your issue?

That fixed the issue!  Make sure people know to use command prompt as Admin, and just have them copy/paste that command into the prompt.  Then find the java setting that is forcing to 256M and delete that line.  Good detective work.  Thanks!