# Zyte headless proxy docker build fails: incorrect CA certificate checksum
## The problem
Building the zyte-smartproxy-headless-proxy docker image fails with an incorrect CA certificate checksum. The Dockerfile downloads Zyte's proxy CA certificate to intercept HTTPS traffic, but the download link/checksum it ships is stale, so the build bails. This blocked several people trying `make docker` over about a year.
## The verified fix
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.
Source: https://github.com/zytedata/zyte-smartproxy-headless-proxy/issues/33