# Runtime compatibility

> A package that works on Node.js does not work on Bun, which is less mature. A share of requests that touched it failed until the package was swapped.

## What happens

A package that works on Node.js does not work on Bun, which is less mature. A share of requests that touched it failed until the package was swapped.

## How to prevent it

Automated tests run against the runtime a Service ships on, and catch the package before a deploy does.

The postmortem opens the first of these that you do not own yet:

- [Automated tests](https://wiki.playquorum.dev/research/testing-culture.md)

## Components it hits

[App Server](https://wiki.playquorum.dev/components/server.md)

## Facts

SEV3 Runtime compatibility
- **First Era:** [Series A](https://wiki.playquorum.dev/eras/series-a.md)
- **Starts at:** SEV3
- **Escalates to:** SEVnull
- **Lasts:** 1.5 min

## See also

- [Incidents](https://wiki.playquorum.dev/incidents.md)

Source: https://wiki.playquorum.dev/incidents/bun-compat