Modding FNF V-Slice: Setup, Mobile Workflow, and Troubleshooting

In the legacy era, many FNF mods were installed by overwriting core files. That was easy to break and hard to reverse. The official V-Slice engine uses Polymod instead, which changes both the mod folder layout and the safest installation workflow.

This article covers official-engine mod compatibility, PC and mobile setup, and the most common failure cases.

Audience: New players

Last verified: 2026-07-01

Builds checked: Desktop v0.8.4 (2026-03-26) and Android v0.8.5 hotfix (2026-04-06)

Before you start: compatibility rules

Official engine vs community engines

If a mod page says it is for Psych Engine, do not expect it to work by dropping it into the official Itch.io or GitHub build.

Match game version to api_version

Every official-engine Polymod mod declares an api_version inside _polymod_meta.json. That version must be compatible with the game build you are running.

How to check:

1. Read your game version from the title screen or pause menu.
2. Open the mod’s _polymod_meta.json.
3. Compare the mod’s api_version with the release line you installed.

As of July 1, 2026, the prepared source material for this series was checked against desktop v0.8.4 (released March 26, 2026) and Android v0.8.5 hotfix (released April 6, 2026). Newer builds may require newer mod packages.

1. PC mod installation standard

The official engine reads mods from a dedicated mods/ directory next to the executable.

Required directory structure

Friday Night Funkin/
├── funkin.exe
└── mods/
    └── YourModFolder/
        ├── _polymod_meta.json
        ├── songs/
        ├── images/
        └── data/

When you open YourModFolder, _polymod_meta.json should be visible immediately. If it is buried under another wrapper folder, the game may ignore it.

Common pitfalls

Nested folder:

wrong: mods/MyMod-v1.0/MyMod/_polymod_meta.json
right: mods/MyMod/_polymod_meta.json

Wrong extension:

• Windows can hide file extensions and leave you with _polymod_meta.json.txt
• enable file extension visibility and confirm the real filename

ZIP mods:

• ZIP mod support exists on newer V-Slice builds
• _polymod_meta.json still needs to be at the root of the archive

2. Official mobile workflow

Official mobile builds use the same Polymod model, but the app data lives inside a mobile sandbox.

Use the official stores:

Figure 1 - Author screenshot of the official Android store listing.

Recommended mobile path

1. Launch official Friday Night Funkin’ on the device.
2. Open OPTIONS.
3. Select OPEN DATA FOLDER.
4. Let the file manager open the app sandbox.
5. Copy the mod folder into the internal mods/ directory.
6. Restart the game.

This is a safer workflow than downloading random repacked “Mod APK” files or relying on older manual folder instructions from unofficial videos.

3. Troubleshooting index

Black screen or instant crash

Likely causes:

• API mismatch between the game build and the mod
• scripts calling functions not supported by your current build

Start by removing all mods, confirming the base game launches, then reintroducing mods one by one.

Mod does not appear in menus

Polymod error popup

Common triggers:

• malformed _polymod_meta.json
• missing required metadata fields
• undeclared dependencies
• script sandbox violations on newer official builds

Song loads but audio is silent

Check:

• use .ogg files rather than .mp3
• filenames match the song metadata exactly
• capitalization matches the expected asset paths

Mod worked before a game update

After major updates, the mod may need a newer api_version or script adjustments. Check the mod author’s release notes before assuming the game itself is broken.

References

Official sources

• Friday Night Funkin’ modding documentation
• The metadata file
• Asset replacement and additions
• FunkinCrew/Funkin - GitHub Releases
• GitHub issue #5366 - Android data folder discussion
• Polymod metadata documentation

Supplementary reference

• Friday Night Funkin’ development overview - Wikipedia