# SH3006: The build's link is busy, closed, or answered what shuyi can't read

Source: https://zafnok.github.io/shuyi-engine/learn/errors/sh3006/

Class: operation, exit code 1.

`attach` reached the build and said hello, then the link failed: another
client is attached already (a build takes one at a time), the build
closed the link or quit while answering, it didn't answer in time (a
build suspended for long, say), or it answered something this `shuyi`
can't read. An MCP session attached over the link ends with it.

**How to fix it.** Detach the other client (stop its `attach`, or the
agent's session holding it), or start the build again, then attach
again.

For example:

```text
attach: error[SH3006]: another client is attached to the build at 127.0.0.1:7357
```