Fixing handshake failure (-9824) errors

Current guidance: This guide applies to Textual 7.0.3 and later. Prefer asking the network to support modern cipher suites, and treat the older list as a temporary workaround for a specific server. See certificate and security troubleshooting.

To encourage stronger security, the list of cipher suites that Textual prefers was changed in version 7.0.0. It turns out that a lot of Internet Relay Chat (IRC) servers are not adequately configured to handle this change.

This guide will instruct you how to revert to the list of cipher suites preferred by version 5.2.7 of Textual.

Prerequisite

If you are the administrator of a server affected by this change, then it is encouraged that you support the new cipher suites, instead of of forcing users to change which they use. To view a list of cipher suites to support, see this list.

If the paragraph above does not apply to you, then continue reading.

Steps

Starting with version 7.0.3, Textual has a preference that controls which list is used.

To change this preference, follow these steps:

1. Open Server Properties using the keyboard combination Command U
2. In the window that appears, click Network Socket under the Advanced section of the navigation list
3. Change the value of the control labeled Cipher suites to Version 5.2.7 list of cipher suites
4. Save

For visual reference, this section of Server Properties appears similar to the following: