OJS-3.3.0-6 issues with Quicksubmit plugin: Undefined variable newFile and slowness

hi all,
I am testing a migration from OJS2.x to OJS3.3.0-6, and I have found some important details:

  • When I add an XML it takes about 30sec to finish (a small XML file).
  • Adding an HTML also takes about 30sec to finish uploading.
  • It does not allow drag & drop of .CSS .JPG or .PNG files.
  • When uploading a .CSS from the button, it also takes about 20-30sec to finish.
  • When finished, the uploading process takes the sum of all previous files (approx 1 min).
  • The log file shows the following:
    PHP Notice: Undefined variable: newFile in /web/htdocs/opendata/plugins/importexport/quickSubmit/QuickSubmitForm.inc.php on line 312, referer: http://opendata.biblio.uanl.mx/index.php/contexto/management/importexport/plugin/QuickSubmitPlugin/saveSubmit

This error is displayed depending on the number of files sent (in my case I added three submissions, and I got this message three times).

any ideas?