CocoaPods "CDN: trunk Repo update failed" in CI

By Daniel Zoghalchali·Latchkey

CocoaPods could not reach the CDN that serves its spec index. The request timed out or returned a 5xx - a transient network failure on the CocoaPods CDN, not a problem with your Podfile.

What this error means

pod install prints "CDN: trunk Repo update failed" with a timeout or HTTP 5xx, often mid-fetch of the spec index. Re-running the job usually succeeds with no change - the hallmark of a transient network issue.

pod output

[!] CDN: trunk Repo update failed - 10 error(s):
CDN: trunk URL couldn't be downloaded:
https://cdn.cocoapods.org/all_pods_versions_a_b_c.txt
Response: Timeout was reached

Common causes

Transient CDN outage or slowness

The CocoaPods CDN briefly timed out or returned a 5xx. These blips clear on their own and are unrelated to your dependencies.

Restrictive network or low timeout on the runner

A proxy, DNS hiccup, or a short default timeout can make a slow-but-working CDN look failed on a congested runner.

How to fix it

Retry the install

Because this is transient, a simple retry usually clears it.

Terminal

for i in 1 2 3; do pod install && break || sleep 15; done

Pre-fetch / cache the spec repo

Cache CocoaPods state between runs so a flaky CDN matters less, and refresh once up front.

.github/workflows/ci.yml

- uses: actions/cache@v4
  with:
    path: ~/.cocoapods
    key: pods-${{ hashFiles('Podfile.lock') }}
- run: pod install --repo-update

How to prevent it

Cache ~/.cocoapods keyed on Podfile.lock.
Wrap pod install in a small retry loop for CDN flake.
Commit Podfile.lock so resolution is deterministic and cacheable.

Frequently asked questions

What causes ""CDN: trunk Repo update failed""?