Fix cancel button not working when uploading a file on the new issue page

app/assets/javascripts/dropzone_input.js

@@ -119,11 +119,9 @@ export default function dropzoneInput(form) {
   // removeAllFiles(true) stops uploading files (if any)
   // and remove them from dropzone files queue.
   $cancelButton.on('click', (e) => {
-    const target = e.target.closest('.js-main-target-form').querySelector('.div-dropzone');
-
     e.preventDefault();
     e.stopPropagation();
-    Dropzone.forElement(target).removeAllFiles(true);
+    Dropzone.forElement($formDropzone.get(0)).removeAllFiles(true);
   });
   // If 'error' event is fired, we store a failed files,

changelogs/unreleased/jivl-fix-cancel-button-file-upload-new-issue.yml

+---
+title: Fix cancel button not working while uploading on the new issue page
+merge_request: 15137
+author:
+type: fixed

spec/features/issues_spec.rb

@@ -583,6 +583,16 @@ describe 'Issues' do
         expect(page.find_field("issue_description").value).not_to match /\n\n$/
       end
+
+      it "cancels a file upload correctly" do
+        dropzone_file([Rails.root.join('spec', 'fixtures', 'dk.png')], 0, false)
+
+        click_button 'Cancel'
+
+        expect(page).to have_button('Attach a file')
+        expect(page).not_to have_button('Cancel')
+        expect(page).not_to have_selector('.uploading-progress-container', visible: true)
+      end
     end
     context 'form filled by URL parameters' do