Wordpress Upload error

Are you using a plug-in for the upload?  There are only a few recognizable upload errors.  In PHP you can detect these as shown here:

// ARRAY OF ERRORS THAT MAY BE REPORTED IN $_FILES[]["error"] (THERE IS NO #5)
$errors = array
( UPLOAD_ERR_OK         => "Success!"
, UPLOAD_ERR_INI_SIZE   => "The uploaded file exceeds the upload_max_filesize directive in php.ini"
, UPLOAD_ERR_FORM_SIZE  => "The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form"
, UPLOAD_ERR_PARTIAL    => "The uploaded file was only partially uploaded"
, UPLOAD_ERR_NO_FILE    => "No file was uploaded"
, 5                     => "UNDEFINED ERROR #5"
, UPLOAD_ERR_NO_TMP_DIR => "Missing a temporary folder"
, UPLOAD_ERR_CANT_WRITE => "Cannot write file to disk"
, UPLOAD_ERR_EXTENSION  => "A PHP extension stopped the file upload"
)
;

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I am using the wordpress upload, not any plugins, not see any specific errors,
When I look from the backend the file does get uploaded, so I believe its trying to read part its crashing.

So when I go to dashboard Media I see that its thinking but does not show any existing file, and after uploading the file get uploaded but then gives this error

 “An error occurred in the upload. Please try again later.”

Looks like When Adding media through list works

Grid - does not work
Add media to page/post does not work
Add Avatar does not work

It looks like something to do with javascript on the site,

Any idea how this can be fixed, It is a very critical issue

Are you still having the issue?

There's a set of instructions for resolving the problem here, and they look thorough:
https://sebastian.expert/fix-wordpress-an-error-occurred-in-the-upload-please-try-again-later/

Let us know how you go.