allowedExtensions is always false

[thpa]

I am using TYPO3 11 and PHP 8.1, non-composer mode.

Every time i try to select a file i get the alert box, that the file extension ist not allowed, but it is one of the allowed.
I tried different files with the file extensions.

I tried to check the values using in the media_upload.js File if the file extensions are available at this point.
Seems all to be correct.

Actually have no clue to start debugging.

[klodeckl]

Same here. The error occurs if more than one file extension is allowed:
<f:format.raw><mu:widget.upload allowedExtensions="jpg,png,mp4" storage="1" property="media" sizeUnit="MB" maximumSize="20000000" /></f:format.raw>

The error is in the upload viewhelper, the output of the javascript is:
var allowedExtensions= ['jpg,png,mp4'];
but it should be
var allowedExtensions= ['jpg','png','mp4'];

It is not a real fix but I solved it the following way:

In the viewhelper template:
var allowedExtensions= ['<f:format.raw><f:cObject typoscriptObjectPath="lib.replace_comma">{allowedExtensions}</f:cObject></f:format.raw>'];

And this typoscript:
lib.replace_comma = TEXT
lib.replace_comma {
current = 1
stdWrap.replacement {
1 {
search = ,
replace = ','
}
}
}