"Cannot upload file" message

[esteban89]

Image is appearing temporarily, then a pop message saying "Cannot upload file" appears and when I click "ok" image dissapears.
Image file is copying into data/files and settings are writing to storage/cache/data/files

Any idea what's going on? Been trying to fix it for hours without any luck

I modified connector and added &responseType=json in the end and now I'm not getting a popup message but I'm getting ERR_CONNECTION_REFUSED in the console for the uploaded image

In the logs I'm getting the following error:
[2020-06-14T03:24:00.253143+00:00] CKFinder.WARNING: ErrorException: Since symfony/http-foundation 5.1: The "Symfony\Component\HttpFoundation\JsonResponse::create()" method is deprecated, use "new CKSource\CKFinder\Response\JsonResponse()" instead.

[esteban89]

Fixed it: for future reference if anyone has this problem: I was getting the image from localhost/ instead of localhost:8000/

[d4rkr3pt0r]

Fixed it: for future reference if anyone has this problem: I was getting the image from localhost/ instead of localhost:8000/

This happens when CSRF token in not sending or is invalid because destination URL is wrong (as you said)

[ianOPF]

Fixed it: for future reference if anyone has this problem: I was getting the image from localhost/ instead of localhost:8000/

Could you tell me how to get image from localhost/?