# XO1303: module version not in the cache while offline

With XO_OFFLINE=1 or `--offline`, the toolchain never touches the network: every required module version must already be in the module cache ($XO_MODCACHE, default \<user cache dir>/xo/mod) or in the main module's vendor/. This version is in neither. Fetch it once while online (`xo mod tidy`, `xo get <path>@<version>`, or any build), or commit a vendor/ directory with `xo vendor`. See core 4.2 and decision 0086.

## Example

```xo
XO_OFFLINE=1 xo build .   # billing v1.4.0 was never fetched
```

## Fix

```xo
xo mod tidy               # online, once
XO_OFFLINE=1 xo build .   # from the cache from now on
```

Run `xo explain XO1303` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).