# Compatibility dates

The Zuplo MCP Gateway requires `compatibilityDate >= 2026-03-01` in
`zuplo.jsonc`.

```jsonc
// zuplo.jsonc
{
  "version": 1,
  "compatibilityDate": "2026-03-01",
}
```

:::caution

The build fails if your project uses any MCP Gateway feature (the
`McpProxyHandler` handler or an `mcp-*-inbound` policy) with a compatibility
date older than `2026-03-01`. Bump the date in `zuplo.jsonc` before adding those
features.

:::

New Zuplo projects default to a recent compatibility date, so this only applies
to existing projects being upgraded to use the MCP Gateway.

For background on Zuplo's compatibility-date system in general, see
[Compatibility dates](../../programmable-api/compatibility-dates.mdx).