8.4 KiB
Troubleshooting - RetroBIOS
Diagnosis guide organized by symptom. Each section describes what to check and how to fix it.
Game won't start / black screen
Most launch failures are caused by a missing or incorrect BIOS file.
Check if the BIOS exists:
python scripts/verify.py --platform retroarch --verbose
python scripts/verify.py --system sony-playstation
Look for MISSING entries in the output. A missing required BIOS means the core
cannot start games for that system at all.
Check if the hash matches:
Look for untested entries in the verify output. This means the file exists but
its hash does not match the expected value. Common causes:
- Wrong region (a PAL BIOS instead of NTSC, or vice versa)
- Wrong hardware revision (e.g. SCPH-5501 vs SCPH-1001 for PlayStation)
- Corrupted download
Each system page on the site lists the expected hashes. Compare your file's MD5 or SHA1 against those values.
Wrong region BIOS:
Some cores require region-specific BIOS files. A Japanese BIOS won't boot North American games on cores that enforce region matching. Check the emulator profile for your core to see which regions are supported and which files correspond to each.
BIOS not found by emulator
The file exists on disk, but the emulator reports it as missing.
Wrong directory:
Each platform expects BIOS files in a specific base directory:
- RetroArch, Lakka:
system/inside the RetroArch directory - Batocera:
/userdata/bios/ - Recalbox:
/recalbox/share/bios/ - RetroPie:
~/RetroPie/BIOS/
Some cores expect files in subdirectories (e.g. dc/ for Dreamcast, pcsx2/bios/
for PlayStation 2). Check the path: field in the emulator profile for the exact
expected location relative to the base directory.
Wrong filename:
Cores match BIOS files by exact filename. If a core expects scph5501.bin and your
file is named SCPH-5501.BIN, it won't be found on platforms that do exact name matching.
Check the emulator profile for the expected filename and any aliases listed under
aliases:. Aliases are alternative names that the core also accepts.
Case sensitivity:
Linux filesystems are case-sensitive. A file named Bios.ROM won't match a lookup
for bios.rom. Windows and macOS are case-insensitive by default, so the same
file works there but fails on Linux.
Batocera's verification uses casefold() for case-insensitive matching, but
the actual emulator may still require exact case. When in doubt, use the exact
filename from the emulator profile.
Hash mismatch / UNTESTED
verify.py reports UNTESTED for a file.
The file exists and was hashed, but the computed hash doesn't match any expected value. This means you have a different version of the file than what the platform or emulator expects. The reason field shows the expected vs actual hash prefix.
To find the correct version, check the system page on the site. It lists every known BIOS file with its expected MD5 and SHA1.
UNTESTED:
On existence-only platforms (RetroArch, Lakka, RetroPie), the file is present
but its hash was not verified against a known value. The platform itself only
checks that the file exists. The --verbose flag shows ground truth data from
emulator profiles, which can confirm whether the file's hash is actually correct.
The .variants/ directory:
When multiple versions of the same BIOS exist (different revisions, regions, or
dumps), the primary version lives in the main directory and alternatives live in
.variants/. verify.py checks the primary file first, then falls back to
variants when resolving by hash.
If your file matches a variant hash but not the primary, it's a valid BIOS -- just not the preferred version. Some cores accept multiple versions.
Pack is missing files
A generated pack doesn't contain all the files you expected.
Severity levels:
verify.py assigns a severity to each issue. Not all missing files are equally
important:
| Severity | Meaning | Action needed |
|---|---|---|
| CRITICAL | Required file missing or hash mismatch on MD5 platforms | Must fix. Core won't function. |
| WARNING | Optional file missing, or hash mismatch on existence platforms | Core works but with reduced functionality. |
| INFO | Optional file missing on existence-only platforms, or HLE fallback available | Core works fine, BIOS improves accuracy. |
| OK | File present and verified | No action needed. |
Focus on CRITICAL issues first. WARNING files improve the experience but aren't strictly necessary. INFO files are nice to have.
Large files (over 50 MB):
Files like PS3UPDAT.PUP, PSVUPDAT.PUP, and Switch firmware are too large for the
git repository. They are stored as GitHub release assets under the large-files
release and downloaded at build time.
If a pack build fails to include these, check your network connection. In offline
mode (--offline), large files are only included if already cached locally in
.cache/large/.
Data directories:
Some cores need entire directory trees rather than individual files (e.g. Dolphin's
Sys/ directory, PPSSPP's assets/). These are fetched by refresh_data_dirs.py
from upstream repositories.
In offline mode, data directories are only included if already cached in data/.
Run python scripts/refresh_data_dirs.py to fetch them.
verify.py reports errors
How to read and interpret verify.py output.
Status codes:
| Status | Meaning |
|---|---|
ok |
File present, hash matches (or existence check passed) |
untested |
File present, hash not confirmed against expected value |
missing |
File not found in the repository |
Hash and size mismatches are reported as untested with a reason field
showing expected vs actual values (e.g., expected abc123… got def456…).
Reading the output:
Each line shows the file path, its status, and severity. In verbose mode, ground truth data from emulator profiles is appended, showing which cores reference the file and what validations they perform.
scph5501.bin ok [OK]
dc_boot.bin missing [CRITICAL]
gba_bios.bin untested [WARNING]
Cross-reference section:
After per-file results, verify.py prints a cross-reference report. This lists
files that emulator cores need but that the platform YAML doesn't declare. These
files are still included in packs automatically, but the report helps identify
gaps in platform coverage data.
The cross-reference uses resolve_platform_cores() to determine which emulator
profiles are relevant for each platform, then checks whether each profile's files
appear in the platform config.
Filtering output:
# By platform
python scripts/verify.py --platform batocera
# By emulator core
python scripts/verify.py --emulator beetle_psx
# By system
python scripts/verify.py --system sony-playstation
# By hardware target
python scripts/verify.py --platform retroarch --target switch
# JSON for scripted processing
python scripts/verify.py --platform retroarch --json
Installation script fails
Problems with install.py, install.sh, or download.sh.
Network issues:
The installer downloads packs from GitHub releases. If the download fails:
- Check your internet connection
- Verify that
https://github.comis reachable - If behind a proxy, set
HTTPS_PROXYin your environment - Try again later if GitHub is experiencing issues
Permission denied:
The installer needs write access to the target directory.
- On Linux/macOS: check directory ownership (
ls -la) and run with appropriate permissions. Avoid running as root unless the target directory requires it. - On Windows: run PowerShell as Administrator if installing to a protected directory.
Platform not detected:
install.py auto-detects your platform by checking for known config files. If
detection fails, specify the platform manually:
python install.py --platform retroarch --dest ~/RetroArch/system/
python install.py --platform batocera --dest /userdata/bios/
Use python install.py --help to see all available platforms and options.
Pack not found in release:
If the installer reports that no pack exists for your platform, check available releases:
python scripts/download.py --list
# or
bash scripts/download.sh --list
Some platforms share packs (Lakka uses the RetroArch pack). The installer handles this mapping automatically, but if you're downloading manually, check which pack name corresponds to your platform.