File not found error during production distribution on case-sensitive filesystems

Direct Answer

Ren'Py does not include a built-in validation tool that audits asset paths for case-sensitivity mismatches. The Launcher's Lint Project command checks script syntax and reference validity on the current filesystem, but it runs on the developer's OS—so on Windows it will not surface case mismatches that later break on Linux or Android.

Why This Happens

Windows filesystems (NTFS, FAT32) are case-insensitive by default. Ren'Py running on Windows will load bg_park.png even if the script references bg_Park.png. When the project is packed into .rpa archives or deployed to Linux/Android, the underlying filesystem becomes case-sensitive, and the engine can no longer resolve the mismatched path.

Recommended Audit Method

Write a small Python script (or an init python block in your project) that:

1. Walks the game/ directory with os.walk or pathlib.Path.rglob to build a set of actual filenames with exact casing.
2. Parses every .rpy file for quoted asset strings used in image, scene, show, play, sound, movie, background, cursor, and similar statements.
3. Compares each referenced path against the on-disk set using case-sensitive matching.
4. Reports every reference that has no exact-case match.

# Example standalone audit script (run from project root)
import os, re, pathlib

GAME_DIR = pathlib.Path("game")
# 1. Collect actual files with exact case
actual = {p.relative_to(GAME_DIR).as_posix() for p in GAME_DIR.rglob("*") if p.is_file()}

# 2. Find asset references in .rpy files
asset_pattern = re.compile(r'"([^"]+\.(?:png|jpg|webp|ogg|mp3|wav|mp4|webm|ttf|otf))"')
mismatches = []
for rpy in GAME_DIR.rglob("*.rpy"):
    text = rpy.read_text(encoding="utf-8")
    for m in asset_pattern.finditer(text):
        ref = m.group(1).replace("\\", "/")
        if ref not in actual:
            mismatches.append((rpy, m.start(), ref))

# 3. Report
if mismatches:
    for f, pos, ref in mismatches:
        line = f.read_text(encoding="utf-8")[:pos].count('\n') + 1
        print(f"{f}:{line}: case mismatch → {ref}")
else:
    print("All asset references match on-disk casing.")

Prevention Strategy

Adopt a single casing convention—all lowercase is the most common—for both asset filenames and every script reference. Enforce it with a pre-commit hook or CI check that runs the audit script above.

Verification Before Release

The only definitive confirmation is running the packaged build on a case-sensitive filesystem. Options:

• Boot a Linux live USB or container (Docker/WSL2 with a case-sensitive mount).
• Deploy to an Android device/emulator and exercise every scene.
• Inspect the generated .rpa with unzip -l or 7z l to verify stored filenames match references exactly.

One Diagnostic Detail

If you already run CI on Linux, does the pipeline execute the built game (or at least the Ren'Py lint command) on that runner? That single fact changes whether you need a local audit script or can rely on CI to catch mismatches.