This post will be updated in sync with Minecraft Forum's FAQ Thread. Please do not ask for tech support here; use #minecrafthelp IRC Chat for that.

0. 1.9 refusing to launch (FIXED!)  

When Mojang pushed out 1.9.1-pre1/2, they accidentally marked 1.9 as a snapshot, causing the launcher to delete 1.9, making users unable to launch the game. There is no ETA when this will be fixed. To work around this issue, change your Launcher profile to use version 1.9 explicitly (Edit Profile -> Use Version -> Select "snapshot 1.9")

1. Downgrading

As always, downgrading is not, was never and will never be officially supported! Please do not run 1.9 worlds in 1.8.

2. Intel Integrated GPU and Random Crashing

Some people with Intel integrated GPUs may see the game crashing from memory access violations. The crash log looks like this:

# A fatal error has been detected by the Java Runtime Environment: # # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffb84b1172c, pid=7928, tid=9892 # # JRE version: Java(TM) SE Runtime Environment (8.0_25-b18) (build 1.8.0_25-b18) # Java VM: Java HotSpot(TM) 64-Bit Server VM (25.25-b02 mixed mode windows-amd64 compressed oops) # Problematic frame: # C [ig8icd64.dll+0x60172c] # # Failed to write core dump. Minidumps are not enabled by default on client versions of Windows # # If you would like to submit a bug report, please visit: # http://ift.tt/19dgsTD # The crash happened outside the Java Virtual Machine in native code. # See problematic frame for where to report the bug. # 

This is because of a memory leak caused by Intel's drivers (i.e. faulty drivers). This mainly affects 7th to 9th Generation Intel HD Graphics (ig7xxxxx.dll, ig8xxxxx.dll, ig9xxxxx.dll) which ships with 3rd Generation to 6th Generation Intel Core Processors. In layman's terms, if your Intel CPU is Ivy Bridge (Model number ix-3xxx), Haswell (4xxx), Broadwell (5xxx) or Skylake (6xxx), you may be affected.

Until Intel fixes their drivers, to work around this issue, make sure you have the latest drivers installed and set VBO and VSync to On in Video Settings (Options -> Video Settings -> Use VSync/Use VBO -> On). Additionally, try allocating more RAM to Minecraft.

(Bug report here)  

3. OpenGL Requirements

The OpenGL requirement for 1.9 stays at OpenGL 1.3 (according to internal sources). Please report back if you have a OpenGL 1.3 only system that refuses to run Minecraft even at very low graphics settings.

4. Graphics Glitching For No Reason After Upgrading

Minecraft 1.9 makes use of even more advanced OpenGL features than before. If your graphics suddenly started giltching since upgrading to 1.9, chances are that your graphics drivers are out of date.

Make sure you have the latest drivers installed and set VBO and VSync to On in Video Settings (Options -> Video Settings -> Use VSync/Use VBO -> On). If you are on a laptop with switchable graphics, you may also want to check that your computer is indeed using the dedicated graphics card.

Nvidia Optimus Instructions

AMD Switchable Graphics Instructions

5. Common Issues We Are Aware Of

Here are some common issues we are aware of that is not listed above. We at #MinecraftHelp are constantly investigating the cause; if you think you have more information, please drop by #minecrafthelp and ask to speak of one of the ops. Thanks!

• Extreme lag on 1.9 worlds (not experienced before in 1.8)
• Multiplayer lag in 1.9
• Upgrading worlds from 1.8 to 1.9 seem to break things (this is due to major changes on how entities rendering is handled)
• LAN stops working randomly (from our limited experience, restarting the game seems to fix it sometimes; check if 1.8 LAN works before reporting the problem)