The Workspace Won't Start

Almost every failure here happens before the timer starts, which means no assessment time was lost. Work through these in order.

The device check fails

Browser not supported — the candidate needs a recent Chrome or Edge. Safari and Firefox do not currently support everything the runtime requires.

Required features unavailable — usually cross-origin isolation or SharedArrayBuffer being blocked. Common causes are a managed corporate browser policy, a privacy extension, or a strict content blocker. Try a normal window with extensions disabled, then a personal machine.

Not enough memory — close tabs and applications and retry. Under 8 GB of RAM, a different machine is needed.

Mobile device — no workaround. The workspace needs a laptop or desktop.

The download stalls

The runtime is a few hundred megabytes on first use. On a weak or metered connection this takes a while and can appear stuck.

It is cached afterwards, and it costs no assessment time. Ask the candidate to run the check on a better connection ahead of the assessment.

Ready, but Start does nothing

Usually storage. The runtime caches in browser storage, and a browser with almost no quota left, or one in private browsing, cannot hold it.

Ask the candidate to leave private browsing, free up disk space, and reload.

It started and then froze

Most often memory pressure from everything else on the machine. The candidate should close other applications and reload the tab — work is preserved locally and the attempt resumes.

If it does not recover, see An Assessment Was Interrupted.

Nothing above worked

Email support@ducker.ai with the candidate's browser and operating system version and the device check result, which they can copy from the check screen. Include the assessment name and the invitation.