# Source: https://www.aptible.com/docs/how-to-guides/troubleshooting/common-errors-issues/private-key-match-certificate.md

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# 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).