Add or select media upload modal broken upon image upload

I am facing the same. But I couldn't reproduce it locally, only in Pantheon's staging environment. as @bsingh reported, there are differences in responses between cases that work and cases that don't. Happens randomly, and doesn't seem to have a pattern.

With error:

"ajax":{
            "auto_select_handler":{
               "callback":"::updateFormCallback",
               "wrapper":"media-library-wrapper",
               "event":"auto_select_media_library_widget",
               "url":"\/media-library?...",
               "dialogType":"ajax",
               "submit":{
                  "_triggering_element_name":"auto_select_handler"
               }
            }
         }

Without error:

"ajax":{
    "edit-submit--M799kaIDOac":{...}
    ...
    "auto_select_handler":{...}
    ...
}

I tried a patch to add the missing libraries (in my case: file/drupal.file and dropzonejs/integration), but the problem still persists.

For those hosting with Pantheon:

Pantheon has a known issue with DropzoneJS, which is used for the Media Entity DropzoneJS widget and Media Bulk Upload module.

The module does not interact will with multiple-container environments, such as Pantheon, and is known to cause issues within the platform itself, which is what the site is currently experiencing.

see Pantheon's documentation here: https://docs.pantheon.io/modules-known-issues#dropzonejs

Any update on this issue? I am also facing this issue in my production environment but not on Pantheon.

As mentioned by @nchristensen - this is related to the server/hosting environments.

Acquia has something similar: https://docs.acquia.com/cloud-platform/manage/files/broken/