Hello,
Recently, my apps is giving the errors within chrome instead of in the console, losing the track of what happens on the way. I don’t recall doing anything that would lead to that change (appart from a pip upgrade eventually)
I don’t have a simplified example for it now, but is it a feature that is expected now?
Thanks
Marc
February 28, 2026, 4:55pm
2
No. Try to look in the server logs. Try to look in the browsers developer console.
There might be more info there. Feel free to share.
No error there either.
From what i understand, it happens when an error happens when loading the app (before it has time to load
The inspected object is:
<div class="bk-panel-models-markup-HTML markdown alert alert-danger" style="width: calc(100% - 10px); min-width: 0px;"></div>
...
<style>
:host(.pn-loading):before, .pn-loading:before {
background-color: #c3c3c3;
mask-size: auto calc(min(50%, 300px));
-webkit-mask-size: auto calc(min(50%, 300px));
}</style>
<div style="width: 100%; min-width: 0px; visibility: visible;"><p><b>IndexError</b></p>
<pre style="overflow-y: auto">list index out of range</pre></div>
does it help?
Hey,
I could trace back to the source of my problem
holoviz:main ← tmoulignier:main
opened 03:53PM - 06 Mar 26 UTC
Hello,
Between the versions 1.8.2 and 1.8.3, a behavior was changed in the er… ror handler. If we serve a function that runs into a python error, the behavior goes from
1.8.2 : Error 505 appearing in the browser, full traceback in the console
to
1.8.3 : Simple error message in the browser, nothing in the console
The loss of traceback turns debugging into a nightmare.
The simple error message seem to come from this, whose code actually changed between the two versions:
https://github.com/holoviz/panel/blob/v1.8.3/panel/io/handlers.py#L369
I propose to replace the simple e put in the string by its traceback, and print it to have it in the console to benefit from IDE console features.
I propose a pull request with the associated changes.
Thanks,
Thibault