## TL;DR

The CA certificate download in the repo was stale; fixed in https://github.com/zytedata/zyte-smartproxy-headless-proxy/pull/63. If you're on an old checkout, the same fix is to replace the zyte-proxy-ca.crt download with the current certificate published at docs.zyte.com before building.

## Steps

1. The CA certificate download in the repo was stale; fixed in https://github.com/zytedata/zyte-smartproxy-headless-proxy/pull/63. Pull the latest repo and rebuild the image. If you're on an old checkout, the same fix is to replace the zyte-proxy-ca.crt download with the current certificate published at docs.zyte.com before building.

## When to use

You are seeing this: Building the zyte-smartproxy-headless-proxy docker image fails with an incorrect CA certificate checksum. Use this skill when you run into "Zyte headless proxy docker build fails: incorrect CA certificate checksum".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Sources

- https://github.com/zytedata/zyte-smartproxy-headless-proxy/pull/63