Image can't be uploaded by the user from the Frontend

Hello dear Tech Support,

I have encountered a problem when testing how to add a Flexicontent item as a registered User from the frontend on my own Joomla website. Specifically, everything is fine except for the fact that the User wouldn't be able to upload any image into an image field - neither Intro Image nor Full Image. The browse function simply doesn't work.
I don't know what causes this, all I know is that the Image Source setting for the Image Field is Joomla Article Images (into + full). 
And when I try to open a page with the item submission form with a browser console enabled, the error messages are like on the screenshots attached.

Can you please tell me how to fix this problem?

Best regards,
Pavel Mozgovoy

i think you have js problem
2 fact
- jquery conflict with your template
- js compression

Hello

do you mean that if you log as
administrator
or as Super user

then image selection in frontend works ?

No, it doesn't - I log in as my fake registered User from the frontend.
And I've tested it with the Optimize CSS and Optimize JS options OFF in my template - it's a Joomlart template.
It still doesn't work - the browse option is dead so far

Regards

Hello

ok so the issue is not about ACL permissions , it occurs for all users in frontend

Probably the JS error occurs during page load , aka before you even try to click on the selection
You need to look at very first error in the browser"console"

Besides checking the above
Also do this: "Add to you URL"
?tmpl=component

to load the page without module, does it work ?

Hello,
sorry for a big delay in response - two of my other websites had broken down, I had to restore them urgently.
As for your first suggestion, I have tried to open the add new item page in the Firefox browser with the console mode turned on. The first screenshot shows the error, please have a look.

I have also added your code - ?tmpl=component - to the URL  uibp.ru/my-articles.html?view=item&task=add (the add new item page with flexicontent) - 
and the result is shown on the second scrrenshot. To be honest., I just don't know what to do with all this

Thanks for your support, you're really kind
Best regards,
Pavel