Unable to set the private key in Plesk for Linux: Probably, the private key format is invalid

Symptoms

• When uploading an SSL certificate to Plesk, the operation fails with the error message:

  PLESK_ERROR: Unable to set the private key: Probably, the private key format is invalid

• Private Key in the .key file contains the following string:

  -----BEGIN ENCRYPTED PRIVATE KEY----

Cause

The Certificate Private Key part is encrypted.

Resolution

1. Connect to the Plesk server via SSH.

2. Upload the .key file to the server.

3. Decrypt the .key file using the openssl utility:

   # openssl rsa -in my_encrypted.key -out my_decrypted.key

   where:

   • my_encrypted.key – is an uploaded file from step 2
   • my_decrypted.key – a decrypted file that will be created

   Note: To decrypt the key, a passphrase that was entered upon creating the key is required. It will be requested by openssl.

4. Use the new decrypted .key file (In this example, my_decrypted.key) to upload an SSL certificate in Plesk.