Minecraft: Java Edition/Debugging Material

This is a sub-page of Minecraft: Java Edition.

The Java Edition of Minecraft contains a lot of debugging features, and we mean a lot.

Debug Text

In the language files for the game, lines 221 and 3296 to 3320 contain some debug-related strings. They are indeed used by the debugging options shown below.

generator.debug_all_block_states=Debug Mode

debug.prefix=[Debug]:
debug.reload_chunks.help=F3 + A = Reload chunks
debug.show_hitboxes.help=F3 + B = Show hitboxes
debug.clear_chat.help=F3 + D = Clear chat
debug.cycle_renderdistance.help=F3 + F = Cycle render distance (Shift to invert)
debug.chunk_boundaries.help=F3 + G = Show chunk boundaries
debug.advanced_tooltips.help=F3 + H = Advanced tooltips
debug.creative_spectator.help=F3 + N = Cycle creative <-> spectator
debug.pause_focus.help=F3 + P = Pause on lost focus
debug.help.help=F3 + Q = Show this list
debug.reload_resourcepacks.help=F3 + T = Reload resource packs

debug.reload_chunks.message=Reloading all chunks
debug.show_hitboxes.on=Hitboxes: shown
debug.show_hitboxes.off=Hitboxes: hidden
debug.cycle_renderdistance.message=Render Distance: %s
debug.chunk_boundaries.on=Chunk borders: shown
debug.chunk_boundaries.off=Chunk borders: hidden
debug.advanced_tooltips.on=Advanced tooltips: shown
debug.advanced_tooltips.off=Advanced tooltips: hidden
debug.creative_spectator.error=Unable to switch gamemode, no permission
debug.pause_focus.on=Pause on lost focus: enabled
debug.pause_focus.off=Pause on lost focus: disabled
debug.help.message=Key bindings:
debug.reload_resourcepacks.message=Reloaded resource packs

World Type

The debug world selected as the world type.

The debug world in-game.

Introduced in snapshot 14w26a, holding Alt while selecting a world type will grant access to a hidden world type called "Debug Mode" after scrolling through the standard world types. Doing this will hide the other world options.

This world type only consists of all blocks in the game separated by 1-block gaps. Upon starting the world, you will be forced into Spectator Mode where you cannot interact with the world in any way. If you get into Creative Mode and try to break anything, it will instantly respawn. If you do anything that causes a floating block to update (such as stepping on a pressure plate), many copies of that item will be dropped due to the item being recreated rapidly, and as a result the game may freeze.

Key Combinations

To do: A few things. Find out what else is shown on the debugging overlay. Get some screenshots. Document the revisions the debugging overlay itself had gotten.

Pressing F3 in-game brings up a debugging overlay that displays various debugging text, including:

• The version of Minecraft you are playing (as well as the client type, which defaults to vanilla if you're playing an unmodded version of the game).
• Framerate.
• The number of chunk updates.
• Your max framerate.
• Whether you're using Fancy graphics or Fast graphics.
• Your render distance.
• Your current coordinates.
• The coordinates of the block you are currently looking at.
• The coordinates of the chunk you are currently in.
• The direction you are facing (north, east, etc.)
• The biome you are currently in.
• Current light level.
• Current difficulty level (easy being 0.76, medium being 1.54, hard being 2.33).
• Number of days gone by.

Performance Key Combinations

Holding Shift and pressing F3 in-game to open the debugging overlay shows a pie chart of what is using the most resources, and each of the things listed are all color coded separate colors. Doing the same thing but except holding Alt instead of Shift brings up an alternate way of seeing framerates.

Command Key Combinations

Hotkey	Function	Screenshot
F3 + A	Reloads the currently visible chunks in-game.
F3 + B	Toggles the ability to see entity hitboxes (including players).
F3 + C	Manually crashes the game with the reason of "Manually triggered debug crash". You may need to hold it for a few seconds and then release to trigger it.
F3 + D	Clears the chat.
F3 + F	Cycles between the render distances.
F3 + G	Shows the chunk borders.
F3 + H	Toggles the ability to see more specific tool tips (displays their item ID and the damage value to obtain the item).
F3 + N	Switches between Creative Mode and Spectator Mode.
F3 + P	Toggles the function to pause the game when the game loses focus.
F3 + Q	Displays a list of most of the key combinations that can be used.
F3 + T	Reloads the currently used resource packs.

Unused Debug Keys

In the source files of the game, there are references to several unused debug key combinations. Key combinations with the (invalid key <number>) are not assigned to any physical keys, and thus, cannot be pressed.

Hotkey	Function
Numlock	Toggles SectionPath, a debug mode that shows the borders between subchunks (16 x 16 x 16 areas of blocks).
Numpad 5	Toggles SmartCull, also known as chunk culling.
(invalid key 85)	Captures frustum culling data.
Shift + (invalid key 85)	Deletes captured frustum data.
(invalid key 86)	Toggles SectionVisiblity, a debug mode that shows chunk culling data.
F11	Toggles WireFrame. Note that the code to make wireframe mode work is not present as of Minecraft release 1.21.

Debug Stick

To do: Add more screenshots for context and describe its purpose more.

The debug stick is an unused item from Minecraft 1.13's snapshot "17w46a", that uses the texture of the stick and can only be accessed either by using /give @s Minecraft:Debug_Stick or through the Operator Utilities tab in Creative mode. Right clicking will change the state of the block you are hovering on, and left clicking will choose the state you want to edit. Holding Shift while doing either of the actions will do the same action, but reversed.