Video or the classroom will not load

A step-by-step fix for blank video, a stuck classroom, or "it only works on a VPN" — including how to read the /diag report.

Work through these in order. Most problems stop at step 2.

1. Reload

Reload the lesson page. A dropped connection usually comes back on its own.

2. Camera and microphone permission

Look for a blocked-camera icon in the browser's address bar and allow access. Then close any other app holding the camera — another meeting tool will keep it to itself. Reload afterwards.

3. Browser and device

Use a current Chrome, Edge, Safari or Firefox. Very old browsers and some in-app browsers (a link opened inside a messaging app) cannot run the call.

4. Run the connection test

Open /diag on the Classario site — for example app.classario.com/diag. It needs no sign-in and checks each piece in turn.

The Classario connection diagnostics page
CheckWhat a failure means
App serverClassario itself is unreachable from this network.
DatabaseThe app loads but cannot read or save data — often a firewall or proxy.
Live classroom socketLive updates (answers, chat) cannot get through; the page may look frozen.
File transferImages and uploads will not load.
Video serviceThe call cannot connect. This is the one to quote when the video is black.

The page also reports whether video can travel over plain UDP or has to fall back to TLS. School, office and some mobile networks block the UDP that video calls prefer; if only the TLS route works, the call may connect but be poorer quality.

5. If only a VPN makes it work

That points at the network, not at Classario. Try another network — a phone hotspot is the quickest test — and send the /diag results to support. If you are in Russia, use app.classario.ru, which routes around the blocks.

Include the /diag output when you contact support. It turns "video doesn't work" into something the team can act on immediately.