Diagnosing Black Screen on Startup in LÖVE (Love2d) Applications

Recognizable Condition

The game window opens but remains completely black, and no graphics appear even though the process is still running. No error dialog is shown, and the application does not crash.

Cause & Diagnostic Table

Possible Cause	Typical Symptom	Quick Check
Missing or mis‑pathed assets	love.load fails silently; love.draw never runs	Look for "Failed to open file" messages in the console
Infinite loop in love.load or love.update	Window appears but never updates; CPU spikes	Add a print at the start of love.load and see if it appears
Invalid window configuration in conf.lua	Window creation fails; black screen or immediate exit	Check console for "Invalid mode" or "unsupported fullscreen" warnings
love.graphics.clear omitted or drawing off‑screen	Frame buffer not cleared; everything drawn outside view	Verify that love.draw calls love.graphics.clear and uses coordinates within the window

Ordered Checks

1. Launch from a terminal to capture stdout/stderr:

   love /path/to/your/game

   Required permission: read access to the game folder. No special privileges needed.
2. Inspect console output for Lua errors (e.g., "module 'xyz' not found") or LÖVE warnings about video modes.
3. Add trace prints at the entry points of the callbacks:

   function love.load()
       print('love.load start')
       -- … existing code …
       print('love.load end')
   end
   function love.update(dt)
       print('love.update')
   end
   function love.draw()
       print('love.draw')
       love.graphics.clear(0.1,0.1,0.1,1) -- gray background to see if clear works
   end
   

   If only the "love.load start" line appears, the loop is likely stuck in love.load.
4. Verify conf.lua for valid values:

   function love.conf(t)
       t.window.width = 800
       t.window.height = 600
       t.window.fullscreen = false -- change to true only if your GPU supports the mode
       t.window.vsync = true
   end
   

   An unsupported fullscreen resolution will cause the window to be created but not visible.
5. Test a minimal Hello‑World to rule out engine/graphics driver issues:

   function love.load() love.graphics.setBackgroundColor(0.2,0.2,0.5) end
   function love.draw() love.graphics.print('Hello', 400,300) end
   

   Run it with the same love command. If this shows a colored background and text, the LÖVE build and drivers are functional.

Fixes Tied to Findings

• Asset path errors – Adjust paths to be relative to the game root (the virtual filesystem). Use love.filesystem.getInfo('image.png') to confirm existence before loading.
• Infinite loop – Replace blocking I/O or heavy computation with asynchronous callbacks or split work across frames using a state machine or love.timer.sleep for short yields.
• Bad window mode – Choose a resolution listed by love.window.getModes() or run in windowed mode first; then switch to fullscreen after verifying the mode is supported.
• Missing clear or off‑screen drawing – Ensure love.graphics.clear is called at the start of love.draw and that all drawing commands use coordinates within 0..width and 0..height.

Escalation Criteria

If after completing the ordered checks the window is still black:

1. Enable LÖVE’s debug mode by setting t.console = true in love.conf (requires a debug build of LÖVE) to get more detailed OpenGL error messages.
2. Check the GPU driver logs (e.g., dmesg on Linux, Device Manager on Windows) for reports of context creation failures.
3. Try running the game on another machine or with a different graphics adapter to isolate hardware‑specific issues.
4. If the problem persists, consider filing an issue on the LÖVE GitHub repository with the full console output, conf.lua, and a minimal reproducer.