Change the maximum attachment/upload size

[Discourse]

This guide explains how to change the maximum attachment upload size for self-hosted Discourse instances.

Required user level: System Admin

The default attachment upload size limit is 10MB

If you are self-hosting Discourse and need to allow uploads larger than 10 MB, follow the steps below.

Changing the upload size

1. Connect to your server:

• Use SSH to access your server’s command line interface.

2. Edit the configuration file:

• Navigate to the configuration directory and edit the app.yml file:

cd /var/discourse/
nano containers/app.yml

3. Modify the upload parameters:

• Look for the section labeled params. Directly below, add your desired upload size with careful attention to formatting:

params:
  ## Which Git revision should this container use? (default: latest)
  version: latest
  ## Maximum upload size (default: 10m)
  upload_size: 20m

4. Save your changes:

• Press Ctrl+X to exit, then Y to confirm, and Enter to save the changes.

5. Rebuild the Discourse instance:

• Run the following command from the /var/discourse directory:

./launcher rebuild app

6. Update site settings:

• Go to /admin/site_settings/category/files in your Discourse dashboard.
• Adjust max attachment size kb and max image size kb to your preferred size (e.g. 20 MB). The setting UI allows you to enter the value and select a unit (KB, MB, or GB) from the dropdown.

Both settings are capped by the nginx client_max_body_size value, which is controlled by the upload_size param you set in step 3. The site settings cannot exceed this limit.

Last edited by @david 2025-09-29T13:05:48Z

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