Why am I getting a "CDN: trunk URL couldn't be downloaded... Error in the HTTP2 framing layer" error with CocoaPods?

Last updated: October 5, 2026

Context

When running a build with CocoaPods 1.16.0 or later, you may encounter the following error:

CDN: trunk URL couldn't be downloaded... Error in the HTTP2 framing layer

This occurs because the HTTP/2 connection to cdn.jsdelivr.net fails when attempting to download the podspec.

Answer

There are two steps you can take to resolve this issue:

  1. Clear the build cache. Trigger a new build with the "Clear cache" option enabled for your workflow. This forces the runner to pull fresh dependencies instead of relying on a potentially stuck or corrupted cache.

    Image of a FlutterFVM caching settings page showing two cached workflows (ios-workflow on macOS and android-workflow on macOS) with options to Clear all cache and Refresh list.

  2. Bypass the CDN by using the Git specs source. If the issue persists after clearing the cache, add the following line explicitly to the top of your ios/Podfile to bypass the CDN entirely:

    source 'https://github.com/CocoaPods/Specs.git'