Error code 400304: Application is not found

// Detailed description of issue.
Our application is making multiple POST requests to the endpoint:


and all of them are failing with error code 400304: Application is not found. This is followed by SendbirdError: Failed to refresh the session key.

I’ve triple checked that both the APP_ID and USER_ID are valid. In addition, the connection usually succeeds if I refresh the page, before failing again after a few minutes.

// If problem, please fill out the below. If question, please delete.
[SDK Version]
// What version of the SDK are you using?
React UIKit, version 3.3.6

[Reproduction Steps]
// Please provide reproduction steps and, if possible, code snippets.

const configureSession = (sdk: SendbirdGroupChat | SendbirdOpenChat) => {
const sessionHandler = new SessionHandler();
sessionHandler.onSessionTokenRequired = (resolve, reject) => {
return sessionHandler;



// How frequently is this issue occurring?
On every page refresh–after a few minutes after initially successfully connecting.

[Current impact]
// How is this currently impacting your implementation?
A page refresh must be done to reset the connection.

Hello @notey,

Welcome to the Sendbird Community.

This endpoint is intended to be an internal only endpoint and thus should not be called by you. With sessionHandlers, you should be fetching new sessionTokens, not sessionKeys: