> ## Documentation Index
> Fetch the complete documentation index at: https://www.aptible.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Private Key Must Match Certificate

## Cause

Your [Custom Certificate](/core-concepts/apps/connecting-to-apps/app-endpoints/custom-certificate) is malformed or incomplete, or the private key you uploaded is not the right one for the certificate you uploaded.

## Resolution

Review the instructions here: [Custom Certificate Format](/core-concepts/apps/connecting-to-apps/app-endpoints/custom-certificate#format).