> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thrindex.com/llms.txt
> Use this file to discover all available pages before exploring further.

# E0002 — UnsupportedFormatVersion

> The artifact's format version is not recognized by this build of thrindex.

<Warning>E0002: unsupported artifact format version</Warning>

## What happened

The `.thx` artifact declares a format version (`format` field) that this build of `thrindex-sim` does not know how to read.

## Why

The artifact was compiled with a newer version of THRINDEX that introduced a new artifact format. The installed `thrindex-sim` predates that format.

## How to fix

1. **Upgrade thrindex** (recommended): `pip install --upgrade thrindex`. Then retry.
2. **Recompile the model** with the currently installed thrindex version: run `thx.compile(model, "model.thx")` again.
3. If you need to run the artifact on a pinned version of thrindex, check which format that version supports with `thrindex targets`.

## Example

```
E0002: unsupported artifact format version: "m4"
Why: this build of thrindex-sim understands only "m3".
Fix: rebuild the artifact with `thx.compile()` from thrindex >= 0.3.0.
Docs: https://docs.thrindex.com/errors/E0002
```

## Format version history

| Format | THRINDEX version | Notes                        |
| ------ | ---------------- | ---------------------------- |
| m1     | 0.1.x            | Initial release              |
| m2     | 0.1.x            | Added CRC32                  |
| m3     | 0.2.x            | Conv2d support, delay arrays |