> ## 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.

# E0103 — DelayExceedsTargetMax

> A synaptic delay exceeds the target hardware's maximum, and the fallback is reject.

<Warning>E0103: synaptic delay exceeds target maximum</Warning>

## What happened

A synaptic delay in the model is larger than `native_delay_max_steps` for the compilation target, and the target's `delay_fallback` is set to `"reject"`.

## Why

Hardware backends have a maximum delay register size. Loihi 2, for example, supports delays up to 63 timesteps natively. A model requiring delay=100 cannot be mapped to this hardware without emulation — and if emulation is disabled (`delay_fallback="reject"`), compilation fails.

## How to fix

1. **Reduce the delay** to ≤ `max_steps`.
2. **Switch to a target that supports longer delays or emulation**: the `sim` target emulates delays without limit. Use it for development, then reduce delays before targeting hardware.
3. **Use a target with `delay_fallback="emulate"`**: this inserts buffer stages in the network graph, allowing longer delays at the cost of increased model size and memory.

## Example

```
E0103: synaptic delay exceeds target maximum in layer 0 connection 42
Why: delay_steps=80 > native_delay_max_steps=63 for this target, and delay_fallback is "reject".
Fix: reduce the delay to ≤ 63 steps, or use a target that supports longer delays or emulation.
Docs: https://docs.thrindex.com/errors/E0103
```