OSWeb runtime broken on Mindprobe — _setupClickScreen null error
Hello,
I'm experiencing a complete outage on jatos.mindprobe.eu where **all** my OSWeb studies — including previously deployed and confirmed-working ones — fail on the "Building screen" stage. This appears to be a recent server-side regression in the OSWeb runtime.
### The error
Browser console output:
PixiJS 5.3.12 - WebGL 2
text.es.js:1307 Canvas2D: Multiple readback operations using getImageData are faster...
transfer.js:121 file pool embedded in HTML (N files)
transfer.js:246 All audio files have been loaded and decoded
screen.js:202 Uncaught (in promise) TypeError: Cannot read properties of null (reading 'length')
at Screen._setupClickScreen (screen.js:202)
at Parameters._initialize (parameters.js:24)
at Runner._setupContext (runner.js:143)
Tracing the call chain: `this._runner._welcomeText` is `null` when passed to `_setupClickScreen`. The `typeof text === "undefined"` guard at the top of the function does not catch `null` (because `typeof null === "object"`), so the function continues and crashes when reading `.length` on the null text.
### Evidence this is server-side, not study content
1. **Previously-working deployed studies** that ran fine for weeks now produce the same error without any changes from my side.
2. **A reference .osexp** I successfully ran earlier this year now fails identically when re-uploaded.
3. **Multiple .osexp variants** with different headers (with/without `set background`, with/without `set jatos_uuid`, Python `True/False` vs legacy `yes/no` booleans, ASCII vs Turkish titles, with/without inline_javascript blocks, with/without `run_if` conditions) all produce the identical error.
4. Tested across **two Mindprobe accounts** and multiple browsers (Chrome, Firefox, incognito).
### Suspected cause
This looks like a recent OSWeb runtime update or transpilation pipeline change on the Mindprobe server. The failure pattern (identical error on unchanged previously-working studies) is hard to explain otherwise.
Thanks,
Büşra
Comments
Hi Büşra,
I tried my studies with OSWeb on Mindprobe on other JATOS installations and they work, as all other studies do too. But we did an update of the JATOS server on the weekend, so I want to make sure that there is nothing that might have caused your problems. Could you provide me with an example of your study that doesn't work on Mindprobe? Either send me the jzip or make me a member of your study.
Best,
Kristian