SSL Errors When Connecting to Tableau Server Using ECC Key

Published: 11 May 2020
Last Modified Date: 08 Jul 2022


When connecting to a Tableau Server instance which uses an ECC certificate for external SSL, the following errors may occur:

In Tableau Desktop

Cannot connect to Tableau Server. Please check the server name and port and try again.
Error Code: 9F4C5638
Internet communication error: SSL peer certificate or SSH remote key was not OK (
<server address>).

In Tableau Prep Builder

The required SSL certificate might be missing or doesn't match the Tableau Server certificate for "<server address>". Contact your System Administrator.


  • Tableau Server
  • Tableau Desktop
  • Tableau Prep Builder


Use a valid RSA or DSA private key file instead of the ECC key file.


The ability to use of ECC key files when configuring SSL for external HTTP traffic to and from Tableau Server is currently not built into the product.

Additional Information

To check whether the SSL certificate uses Elliptic Curve Cryptography (ECC), carry out the following steps:
  1. Access the Tableau Server instance in a web browser (e.g. Google Chrome).
  2. Click on the padlock icon next to the address bar > Certificate > Details tab.
  3. In the list of fields, look for Signature algorithm.
  4. If the value ends in 'ECDSA', which stands for Elliptic Curve Digital Signature Algorithm, the certificate uses ECC. 

For other SSL certificate requirements when configuring SSL for external HTTP traffic to and from Tableau Server, see this Help document.
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