Two types of issues that are similar but have different fixes.
Just like with many other live-service titles, players can easily run into a number of errors that will impact their experience logging into or playing VALORANT.
The FPS has a dedicated page on Riot Games’ support website due to the sheer number of potential errors that could pop up, and two of those listed error codes are numbered 43 and 46. And because the codes are so closely numbered, the general type of issue is similar between the two.
Error code 43 specifically deals with the VALORANT client timing out for one reason or another, whether that be when logging in or while already signed in. After getting the error, the easiest fix is to restart the Riot Client and try logging in again, which should fix the problem.
If the error persists, you might actually end up dealing with error code 46, which deals not only with log-in issues but general platform downtime as well.
If you run into error code 46, that means the entire VALORANT client is experiencing downtime of some kind. This error should only pop up if the downtime is planned by Riot and allotted to allow engineers to work on the games systems.
You can still potentially fix it if the downtime is unintentional or short by restarting the Riot Client and booting it back up. The other option is that you will simply have to wait.