Unable to download js attachment

Contribute Bug
13

Same problem here. We have js files that run in our own software, nothing that would ever do anything in a browser.

We managed to fix the discourse download problem by moving all uploads to an S3 bucket and setting s3_use_cdn_url_for_all_uploads to true. This essentially bypasses the short-url controller which appears to be the show stopper for js files.

In detail (from my AI which walked me through this):

  1. Set up S3-Compatible Storage (e.g., Cloudflare R2)

Discourse cannot safely serve .js files from the local disk. Move them to a bucket.

  • Bucket: Create a private bucket (e.g., my-discourse-bucket).

  • API Keys: Generate an Access Key and Secret Key.

2. Configure a Custom CDN Domain

In Cloudflare (or your provider), connect a custom domain to your bucket (e.g., cdn.example.com). This ensures files are served as static assets via a direct URL, bypassing the Discourse “security guard.”

3. Update Discourse Settings

In Admin → Settings, configure your S3 details. Crucially, enable the following to ensure Discourse doesn’t try to “sign” the URLs with temporary headers that can break:

  • s3_use_cdn_url_for_all_uploads: Check this box (This is the most important step).

  • s3_cdn_url: Set to https://cdn.example.com.

  • s3_region: Use us-east-1 (for R2 compatibility).

4. Migrate Existing Uploads (optional)

Note: This did NOT work for us for unknown reasons.

To fix old links in existing posts, enter your container and run:

Bash

# Inside /var/discourse
./launcher enter app
rake uploads:migrate_to_s3
rake posts:rebake

Hope this helps someone.