# Cannot join subsessions: Websocket closed before connection is established loop **URL:** \ **Category:** Web\ **Tags:** video-sdk\ **Created:** [August 19, 2025, 10:10pm UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674 "2025-08-19T22:10:09Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![apc](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/apc/32/70811_2.png) [@apc](https://devforum.zoom.us/u/apc)\ **Post date:** [August 19, 2025, 10:10pm UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/1 "2025-08-19T22:10:09Z")
**Description** I’m attempting to build a waiting room using subsessions as described in the developer blog entry “Building a telehealth waiting room with Zoom Video SDK”. If I remove all lines of code up to the `.joinSubsession` in the snippet below, the client successfully connects to the main session. As soon as I call `.joinSubsession`, the app is thrown into a connection loop that never completes. The `await .joinSubsession` promise never fulfills or rejects , and the logs indicated below begin appearing forever. **Browser Console Error** WebSocket connection to ‘wss://zoomiad206247136128rwg.iad.zoom.us/wc/media/95281164371?type=s&cid=5F4E0267-5E17-E02A-6054-C58FAFBE24A9&mode=1’ failed: WebSocket is closed before the connection is established. js\_media.min.js:2 handleRendererTypeInProps() final rendererType=3 gpuBlacklist=undefined 39e4ae1a-81b3-431e-9b27-22f0f800d9a7:1 Sharing Version: 3727 625b5454-3119-4a29-b1e2-c5017be63671:1 WebSocket connection to ‘wss://zoomiad206247136128rwg.iad.zoom.us/wc/media/95281164371?type=s&cid=08480093-56D4-2D7A-5218-DAE32DBADEBD&mode=1’ failed: WebSocket is closed before the connection is established. js\_media.min.js:2 handleRendererTypeInProps() final rendererType=3 gpuBlacklist=undefined da4d9623-cd77-4ca7-88a1-8ce36be7630b:1 Sharing Version: 3727 ec6ea77d-1930-4047-8f0a-1affd63d2779:1 WebSocket connection to ‘wss://zoomiad206247136128rwg.iad.zoom.us/wc/media/95281164371?type=s&cid=764B3A9D-21A0-D309-BC20-F8F670416593&mode=1’ failed: WebSocket is closed before the connection is established. js\_media.min.js:2 Uncaught (in promise) TypeError: Cannot read properties of null (reading ‘remoteDescription’) js\_media.min.js:2 Uncaught (in promise) TypeError: Cannot read properties of null (reading ‘remoteDescription’) js\_media.min.js:2 Uncaught (in promise) TypeError: Cannot read properties of null (reading ‘remoteDescription’) js\_media.min.js:2 Uncaught (in promise) TypeError: Cannot read properties of null (reading ‘remoteDescription’) js\_media.min.js:2 Uncaught (in promise) TypeError: Cannot read properties of null (reading ‘setRemoteDescription’) js\_media.min.js:2 handleRendererTypeInProps() final rendererType=3 gpuBlacklist=undefined 5dfb116a-14f9-4e3a-88f2-72010ae6abef:1 Sharing Version: 3727 8d0be545-e06c-49d1-8731-4ea0c880ae38:1 WebSocket connection to ‘wss://zoomiad206247136128rwg.iad.zoom.us/wc/media/95281164371?type=s&cid=CD4E3EE9-D9D2-0F0A-0296-76F3A1CE2FA7&mode=1’ failed: WebSocket is closed before the connection is established. … **Which Web Video SDK version?** 2.2.5 **Video SDK Code Snippets** ```auto await client.join("---", "---", "---"); const subsessionClient = client.getSubsessionClient(); const inProgressSubsession = ( await subsessionClient.createSubsessions(["in-progress"]) )[0]; if (inProgressSubsession) { const ownUserId = client.getCurrentUserInfo().userId; const subsessionList = subsessionClient.getSubsessionList(); const session = subsessionList.find( (item) => item.subsessionId === inProgressSubsession.subsessionId ); if (session) { const { userList } = session; if (!userList.find((user) => user.userId == ownUserId)) { userList.push(client.getCurrentUserInfo()); } } await subsessionClient.openSubsessions(subsessionList, { isBackToMainSessionEnabled: false, }); await subsessionClient.joinSubsession( inProgressSubsession.subsessionId ); inProgressSubsessionRef.current = inProgressSubsession; ``` **Device (please complete the following information):** - Device: Macbook Pro - OS: 15.5 - Browser: Chrome - Browser Version: 139.0.7258.67 ---
**Author:** ![vic.yang](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/vic.yang/32/24656_2.png) [@vic.yang](https://devforum.zoom.us/u/vic.yang)\ **Post date:** [August 20, 2025, 2:13am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/2 "2025-08-20T02:13:22Z")
Hey @apc Thanks for your feedback. Could you share some problematic session IDs with us for troubleshooting purposes? Thanks Vic ---
**Author:** ![apc](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/apc/32/70811_2.png) [@apc](https://devforum.zoom.us/u/apc)\ **Post date:** [August 20, 2025, 11:55am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/3 "2025-08-20T11:55:47Z")
Yes of course, thank you @vic.yang. I’ve just generated session ID (key) `ab026e14-6b58-4802-827d-04dc31346a0e (Dvshw1oYR8O4t3rh78zzig==)` to test this. As far as a pattern in the dashboard, every connection attempt generates a 2-3 second long participant row ie Join Time / End Time | 04:52:42 AM | 04:52:45 AM | | --- | --- | | | | So I end up with a lot of those. ---
**Author:** ![apc](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/apc/32/70811_2.png) [@apc](https://devforum.zoom.us/u/apc)\ **Post date:** [August 20, 2025, 1:14pm UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/4 "2025-08-20T13:14:03Z")
As an additional bit of info, I added this right before the join ```auto client.on("connection-change", console.log); await subsessionClient.joinSubsession( inProgressSubsession.subsessionId ); ``` And I see, tied to these websocket warnings, that it constantly repeats these two logs ```auto {state: 'Connected'} WebSocket connection to ... closed before the connection is established {state: 'Reconnecting', reason: 'failover'} ``` ---
**Author:** ![vic.yang](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/vic.yang/32/24656_2.png) [@vic.yang](https://devforum.zoom.us/u/vic.yang)\ **Post date:** [August 21, 2025, 10:11am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/5 "2025-08-21T10:11:10Z")
Hi @apc > Dvshw1oYR8O4t3rh78zzig== Thank you for sharing the session ID. We are investigating the root cause of the issue. Thanks Vic ---
**Author:** ![vic.yang](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/vic.yang/32/24656_2.png) [@vic.yang](https://devforum.zoom.us/u/vic.yang)\ **Post date:** [August 25, 2025, 2:10am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/6 "2025-08-25T02:10:08Z")
Hi @apc > Dvshw1oYR8O4t3rh78zzig== We have identified some potential causes, but we still need you to confirm some information. I will DM you with the relevant questions. Thanks Vic ---
**Author:** ![apc](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/apc/32/70811_2.png) [@apc](https://devforum.zoom.us/u/apc)\ **Post date:** [August 26, 2025, 2:11pm UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/7 "2025-08-26T14:11:50Z")
Thanks @vic.yang , after ensuring that the token carries the `typ: JWT` header, we’re able to successfully connect. Odd that it worked for the main session without it. Still encountering one strange thing behaviorally that I can work around for now, but seems like its not working as expected. If I `await subsessionClient.joinSession`, it never resolves. Instead, I have to subscribe to the connection change to get my code to progress. ```auto subsessionClient.joinSubsession(inProgressSubsession.subsessionId); await new Promise((resolve) => { const onConnectionChange: typeof event_connection_change = ( payload ) => { console.log(`connection change: ${JSON.stringify(payload)}`); if (payload.state === ConnectionState.Connected) { resolve(); client.off("connection-change", onConnectionChange); } }; client.on("connection-change", onConnectionChange); }); ``` ---
**Author:** ![vic.yang](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/vic.yang/32/24656_2.png) [@vic.yang](https://devforum.zoom.us/u/vic.yang)\ **Post date:** [August 27, 2025, 2:36am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/8 "2025-08-27T02:36:57Z")
Hi @apc Thanks for your feedback. > If I `await subsessionClient.joinSession` , it never resolves. It is indeed an issue; we will fix it in the upcoming release (2.2.10 – late August). Thanks Vic ---
**Author:** ![system](https://us1.discourse-cdn.com/flex016/uploads/zoomdeveloper/original/3X/6/1/614bdd549b610bbaa46ff934617683a02bdaa03c.png) [@system](https://devforum.zoom.us/u/system)\ **Post date:** [August 27, 2026, 2:37am UTC](https://devforum.zoom.us/t/cannot-join-subsessions-websocket-closed-before-connection-is-established-loop/136674/9 "2026-08-27T02:37:45Z")
Closed on August 27, 2026, 2:37am UTC This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.