Crash of one leaf

[Nina Bonge]

Hi,

We have already done a few sessions with zTu, today we had the first "crash" - with one participant. The participant could not make any more inputs, we took him into the next stage. There the screen was built correctly, inputs were possible, but not pressing the "Next button". Calling the link in other browsers, refreshing the page, wasn't successful. Do you have a solution for the next time?

Best

Nina

[Melisa Demirovic]

Hi,

Had the same issue today! Any suggestions?

Best,

Melisa

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[Vasudha Chopra]

Hi everyone, 

This happened to us a couple of times as well. A few times it was the numeric keypad which didn't work so we had participants use the keys above the standard QWERTY keypad. One time we hit the ok/continue button on the screen and then things started working. However, a few times when it happened, we were hoping "restart zleaf" to help with this but it didn't. I wonder why this kind of bug has a higher tendency to occur when the total subjects equals 4 clients. 

Can anyone offer any help regarding this? Thank you. 

Sincere regards,

Vasudha

[Max R. P. Grossmann]

Hi folks,

Have y'all tried pressing Alt?

Best,

Max

[Vasudha Chopra]

Hi Max,

Thank you for your response. No, I haven't but will try next time if it happens, is there a specific reason as to why that would help? 

Sincere regards,

Vasudha

[John Mcmahan]

This has been happening at a decent % (maybe 10-15% of the time) and only on a single client. The client is able to click radio buttons and use the mouse but numerical entry from the keyboard does not work.

Best,

John

[Max R. P. Grossmann]

Hi Vasudha,

On occasion, subjects may mistakenly press the Alt key, causing it to be "locked in" – meaning that all other keystrokes and clicks are sent with this modifier. You can sort of simulate this at home. Press Alt and don't release, and then try to do anything. Suddenly everything stops working. We do not know exactly what could cause Alt to be "locked in" however, as this does not usually happen on Windows. But it does seem to happen with zTu, sometimes.

We are currently working on completely solving this issue (by removing Alt from the list of approved keys). I would estimate that this resolves about 70% of cases of subjects not being able to progress. The other cases could be due to client accounts being broken. ./delete_users.sh and reinitialization probably help, but this has its caveats. Since you mentioned that this issue occurs in certain situations, this might be a sensible solution, but make sure to make a backup of your VM beforehand.

New VM versions ship with preinstalled client accounts that are hopefully more robust. Sorry for these issues!





7 May 2021 18:26:54 'Vasudha Chopra' via z-Tree unleashed <z-tree-u...@googlegroups.com>:

> Hi Max,
>
> Thank you for your response. No, I haven't but will try next time if it happens, is there a specific reason as to why that would help? 
>
> Sincere regards,
>
>

> On Friday, May 7, 2021 at 12:19:37 PM UTC-4 Max R. P. Grossmann wrote:
>> Hi folks,
>>
>> Have y'all tried pressing Alt?
>>
>>
>>
>>
>

> You received this message because you are subscribed to the Google Groups "z-Tree unleashed" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to z-tree-unleash...@googlegroups.com.

> To view this discussion on the web visit https://groups.google.com/d/msgid/z-tree-unleashed/c4ad9386-7dd8-4df4-89f6-67b4cc49b2a9n%40googlegroups.com[https://groups.google.com/d/msgid/z-tree-unleashed/c4ad9386-7dd8-4df4-89f6-67b4cc49b2a9n%40googlegroups.com?utm_medium=email&utm_source=footer].

[Max R. P. Grossmann]

John,

This sounds like the clients are somehow damaged. Let's try this (in the Terminal Emulator):

cd ztree-unleashed
git pull # make sure this completes without error
cd scripts
./delete_users.sh
sudo rm /share/install
./init.sh

Note that if you previously "Enable[d] RTF", you need to re-run that.

Best,

Max

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[John Mcmahan]

Hi Max,

This successfully reinstalled the clients. I will report back if we notice improvement.  Thanks for the swift response!

Best,

John

[Vasudha Chopra]

Hello everyone, 

What Max mentioned to me last time about Alt making the keyboard "locked in" seems about right. Today one of the leafs was having an input problem and on a Mac I pressed the "Command" key which happen to solve all the issues (I am guessing it acts as the Alt key). Hope this helps!

Thank you!

Best wishes, 

Vasudha