ACF PRO requires HTTP Basic Auth via Composer against the private repository at composer.advancedcustomfields.com. HTTP 401 errors almost always stem from missing or misconfigured credentials rather than license or network issues. The guide covers how to set up auth.json for local development, use the COMPOSER_AUTH environment
Table of contents
Why Composer returns a 401 when downloading ACF PROHow ACF PRO Composer authentication worksAuthentication depends on where Composer is runningUsing auth.json for local developmentKeeping credentials out of git with environment variablesAuthenticating ACF PRO in GitHub ActionsBedrock workflows and Composer authenticationTrellis Vault and production deploymentsDebugging persistent 401 errorsACF PRO Composer Authentication ChecklistSort: