> ## 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.

# Error Reference

> Every THRINDEX error code — stable, never reused, with what happened / why / how to fix.

All THRINDEX errors carry a stable `E####` code, a human-readable message with four parts: **What happened**, **Why**, **How to fix** (cheapest fix first), and a **Docs link**.

Error codes are organized by subsystem:

| Range       | Subsystem                      |
| ----------- | ------------------------------ |
| E0001–E0099 | Simulator (`thrindex-sim`)     |
| E0101–E0199 | Compiler (`thrindex-compiler`) |
| E0201–E0299 | Conformance / Backend API      |

Codes are never reused. If an error is retired, its number is reserved.

## E00xx — Simulator

| Code                   | Name                       | When                                                      |
| ---------------------- | -------------------------- | --------------------------------------------------------- |
| [E0001](/errors/E0001) | `ArtifactNotFound`         | `.thx` file not found on disk                             |
| [E0002](/errors/E0002) | `UnsupportedFormatVersion` | Artifact format version unrecognized                      |
| [E0003](/errors/E0003) | `UnknownLayerType`         | Layer type not known to this simulator build              |
| [E0004](/errors/E0004) | `DimensionMismatch`        | Layer input/output sizes do not chain                     |
| [E0005](/errors/E0005) | `InvalidLifParam`          | LIF parameter out of valid range                          |
| [E0006](/errors/E0006) | `Base64DecodeError`        | Weight base64 decoding failed                             |
| [E0007](/errors/E0007) | `WeightShapeMismatch`      | Decoded weight count differs from declared shape          |
| [E0008](/errors/E0008) | `JsonParseError`           | Artifact JSON is malformed                                |
| [E0009](/errors/E0009) | `IntegrityCheckFailed`     | CRC32 mismatch — artifact was modified after compilation  |
| [E0010](/errors/E0010) | `InputDimensionMismatch`   | Input spike raster size doesn't match model's first layer |

## E01xx — Compiler

| Code                   | Name                      | When                                              |
| ---------------------- | ------------------------- | ------------------------------------------------- |
| [E0101](/errors/E0101) | `TauMemTooSmall`          | `tau_mem ≤ dt` — neuron would lose all history    |
| [E0102](/errors/E0102) | `RetimingDelayNotInteger` | Delay cannot be retimed to target `dt`            |
| [E0103](/errors/E0103) | `DelayExceedsTargetMax`   | Delay exceeds target hardware maximum             |
| [E0104](/errors/E0104) | `NoNativeDelaySupport`    | Target has no delays and emulation is disabled    |
| [E0105](/errors/E0105) | `EmptyModel`              | Model has no layers                               |
| [E0106](/errors/E0106) | `DimensionMismatch`       | Layer dimensions do not chain correctly           |
| [E0107](/errors/E0107) | `InvalidResetMode`        | `reset` is not `"subtract"` or `"zero"`           |
| [E0108](/errors/E0108) | `IrJsonParseError`        | Graph IR JSON is malformed                        |
| [E0109](/errors/E0109) | `DelayLengthMismatch`     | Delay array length ≠ `in_features × out_features` |

## E02xx — Conformance / Backend

| Code                   | Name                            | When                                                     |
| ---------------------- | ------------------------------- | -------------------------------------------------------- |
| [E0201](/errors/E0201) | `ArtifactParse`                 | Backend could not parse or resolve the artifact          |
| [E0202](/errors/E0202) | `InputShapeMismatch`            | Input tensor prepared for a different model              |
| [E0203](/errors/E0203) | `OutputShapeMismatch`           | Backend output shape differs from reference              |
| [E0204](/errors/E0204) | `Execution`                     | Backend-specific execution failure                       |
| [E0205](/errors/E0205) | `TestSetTooSmall`               | Conformance run has fewer than 100 samples               |
| [E0206](/errors/E0206) | `OutputShapeMismatch` (harness) | Backend output shape differs from reference (per-sample) |
| [E0207](/errors/E0207) | `BackendExecution`              | Backend returned an error during conformance run         |
| [E0208](/errors/E0208) | `ReferenceError`                | Reference simulator errored — indicates a harness bug    |