Diagnosing a Black Window at Startup in LÖVE (Love2D)

The Condition

You launch a LÖVE project and the window opens but stays black. No error dialog appears, the process keeps running, and nothing ever renders. This is distinct from the case where LÖVE shows its built-in error screen (blue background with a traceback) — that screen means the engine found your code and caught an error, which is usually easier to fix. A plain black window with no error output usually means one of three things: the draw loop is running but drawing nothing visible, an error occurred before any error handler could display it, or the main thread is blocked and never reaches the first frame.

Note on scope: this guide assumes a desktop LÖVE 11.x or 12.x install. Behavior on Android/iOS differs, and some details below should be verified against your installed version, since LÖVE's startup and error-handling behavior has changed across releases.

Cause / Diagnostic Table

Possible Cause	Typical Symptom
Uncaught error in love.load before the error handler is effective	Window opens but no frame is ever drawn; error text may only appear on stderr.
Asset load failure (wrong path, wrong case, missing file)	love.graphics.newImage and similar functions raise a Lua error on failure; if this happens during startup the game halts before rendering.
Blocking loop in love.load or love.update	Window appears but never refreshes; OS may mark it "not responding".
Drawing happens, but off-screen or with zero alpha / cleared-over content	No error at all; the loop runs, but output is invisible.
Console output suppressed	Errors exist but you never see them (e.g., launching a fused executable by double-clicking on Windows).

Ordered Checks

1. Run from a terminal and read stderr.

   From a shell, run love /path/to/project (or love . inside the project folder). No special permissions are needed. Many startup errors are printed to stderr even when no on-screen error appears. If you normally launch by double-clicking a .love file or a fused executable, this step alone often reveals the cause.

   Risk: none; read-only.

2. Confirm the entry point exists.

   Check that main.lua exists at the top level of the folder or .love archive you are passing to love. If it is missing, LÖVE normally shows its own "no code to run" style error rather than a black window — so if you see that error instead, this is your answer. Also verify you are pointing love at the project folder, not its parent.

3. Replace love.draw with a minimal known-good draw.

   function love.draw()
       love.graphics.clear(0.2, 0.2, 0.2)
       love.graphics.print("render ok", 100, 100)
   end

   In LÖVE 11+, love.graphics.clear takes color components as floats in the 0–1 range. If this gray window with text appears, your rendering pipeline is fine and the fault is in your original draw or load code. If it does not appear, the problem is earlier — in love.load, a blocked thread, or the launch itself.

4. Audit asset loading.

   Functions like love.graphics.newImage raise an error when the file cannot be loaded — they do not return nil, so a guard like if not img then never triggers. Check existence first, or catch the error:

   local path = "assets/player.png"
   if love.filesystem.getInfo(path) then
       playerImage = love.graphics.newImage(path)
   else
       print("missing asset: " .. path)
   end

   Pay attention to case: Windows and default macOS filesystems are case-insensitive, but Linux and LÖVE's own archive handling are case-sensitive. A path that works on your dev machine can fail after deployment.

5. Detect blocking code.

   Comment out the bodies of love.load and love.update temporarily. If the minimal draw from step 3 now appears, something in those callbacks never returns — typically a while loop waiting on a condition that only the main loop could advance. Re-enable code incrementally to find it.

6. Check your engine version.

   Run love --version in the terminal. Compare it against the API your code uses — for example, color values changed from 0–255 (LÖVE 0.10 and earlier) to 0–1 floats (11.0+), so older code can misbehave or error on newer engines. Verify specific API calls against the wiki for your installed version rather than assuming cross-version compatibility.

Fixes Tied to Findings

• Error during love.load: Fix the underlying error reported on stderr (nil indexing, syntax issue, bad require). Optionally define love.errorhandler (or love.errhand on older versions) to control how errors surface during development.
• Bad asset path: Correct the path and case, confirm with love.filesystem.getInfo, and make sure the asset is inside the folder/archive you actually ship.
• Missing main.lua: Create it at the project root with at least the callbacks you use, or fix the path you pass to love.
• Blocking loop: Restructure so initialization advances a little each frame — e.g., a loading state in love.update that loads one asset per call, or a coroutine that yields between steps — and draw a progress indicator meanwhile.
• Version mismatch: Either update the code to the installed engine's API or run the project with the LÖVE version it was written for.

Escalation Criteria

If the window is still black after all checks:

1. Try a different window configuration to rule out swap-interval or fullscreen quirks, e.g. love.window.setMode(800, 600, {vsync = 0, fullscreen = false}) in love.load, then rerun from the terminal and watch stderr for graphics errors.
2. Run the same project on another machine or OS to separate driver/GPU issues from code issues.
3. Reduce the project to a minimal reproduction — a main.lua with only love.load and a single draw call — and add code back until the failure returns. That minimal case is also what you should post when asking the LÖVE community for help.

Because startup behavior varies across LÖVE releases, treat any version-specific detail here as a hypothesis and confirm it against the documentation for the version reported by love --version.