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
Hi Kristian,
Thank you for getting back to me so quickly! I tried adding you as a member but neither `kri` nor `k.lange@cogsci.nl` exists as a JATOS user on Mindprobe. Could you share your Mindprobe/JATOS username? In the meantime, here's the jzip via Google Drive: https://drive.google.com/file/d/1Z0qSIChCx2RrYgjT83cVdjVelsIbwmNf/view?usp=drive_link
Hi Büşra,
I wasn't able to download the jzip; it tells me "the file is in the bin". But anyway I might have found the culprit in a similar question. Is it possible you have spaces in the filenames of files you load in your study?
The latest version of JATOS is stricter with filenames, e.g. doesn't allow spaces in them. I don't use spaces for various reasons in filenames but OSes do allow them, so JATOS should actually allow them. So I changed it in JATOS' code and it will be part of the next release. In the meantime, to make your study run again, I'd recommend to replace all spaces in your filenames with some other character, e.g., a underscore.
Best,
Kristian
Hi Kristian,
Thanks, I tried the workaround but the issue persists. My pool filenames were already clean (e.g., `A_E_01.jpg`, no spaces), and I replaced spaces in my study title with underscores before re-importing, but the same `screen.js:202 _setupClickScreen` error still occurs.
More importantly, all my other previously-imported studies on Mindprobe that ran successfully for weeks before the update are now also failing with the exact same error, without any changes from my side.
Re-uploaded the .jzip (the previous Drive link was a mistakenly-extracted folder):
https://drive.google.com/file/d/1ZKP0PGEYPhY49XNfouiVVaFmAot_VGtF/view?usp=drive_link
Happy to test any specific config change you suggest.
Best,
Büşra
I saw in your earlier comments that your Mindprobe username is admin . I've now added you as a member to my study `tezdeney2_online`. You should see it in your dashboard.
Hi Büşra,
I run your study and it seemed to have worked for me. I run the jzip from Google Drive and the one where you added me as "admin" on Mindprobe. I tried on Cortex and Mindprobe. I couldn't see any problems and in the console were no errors (see screenshot). If you can point me at the issue, I'll try to help you.
Best,
Kristian
Hi Kristian,
It turned out to be a Chrome cache/extension issue on my end. Thanks again for testing on your side and confirming the study itself was fine.
Best,
Büşra