diff --git a/Makefile.local b/Makefile.local
--- a/Makefile.local
+++ b/Makefile.local
@@ -35,7 +35,7 @@
 
 .PHONY: run-migrations-test
 run-migrations-test:
-	rm -f swh/web/settings/testdb.sqlite3
+	rm -f swh-web-test.sqlite3
 	django-admin migrate --settings=$(SETTINGS_TEST) -v0 2>/dev/null
 
 add-users-test: run-migrations-test
diff --git a/assets/src/bundles/admin/origin-save.js b/assets/src/bundles/admin/origin-save.js
--- a/assets/src/bundles/admin/origin-save.js
+++ b/assets/src/bundles/admin/origin-save.js
@@ -307,20 +307,78 @@
   }
 }
 
+const rejectModalHtml = `
+<form id="swh-rejection-form">
+  <div class="form-group row">
+    <label for="swh-rejection-reason" class="col-4 col-form-label">
+      Rejection reason:
+    </label>
+    <div class="col-8">
+      <select class="custom-select" id="swh-rejection-reason">
+        <option value="custom" selected>Custom</option>
+        <option value="invalid-origin">Invalid origin</option>
+        <option value="invalid-origin-type">Invalid origin type</option>
+        <option value="origin-not-found">Origin not found</option>
+      </select>
+    </div>
+  </div>
+  <div class="form-group row">
+    <textarea class="form-control" id="swh-rejection-text"></textarea>
+  </div>
+  <button type="submit" class="btn btn-default float-right" id="swh-rejection-submit">
+    Reject
+  </button>
+</form>
+`;
+
 export function rejectOriginSaveRequest() {
   const selectedRow = pendingSaveRequestsTable.row('.selected');
+  const rowData = selectedRow.data();
   if (selectedRow.length) {
     const rejectOriginSaveRequestCallback = async() => {
-      const rowData = selectedRow.data();
-      const rejectSaveRequestUrl = Urls.admin_origin_save_request_reject(rowData['visit_type'], rowData['origin_url']);
-      await csrfPost(rejectSaveRequestUrl);
+      $('#swh-web-modal-html').modal('hide');
+      const rejectSaveRequestUrl = Urls.admin_origin_save_request_reject(
+        rowData['visit_type'], rowData['origin_url']);
+      await csrfPost(rejectSaveRequestUrl, {},
+                     JSON.stringify({note: $('#swh-rejection-text').val()}));
       pendingSaveRequestsTable.ajax.reload(null, false);
     };
 
-    swh.webapp.showModalConfirm(
-      'Reject origin save request ?',
-      'Are you sure to reject this origin save request ?',
-      rejectOriginSaveRequestCallback);
+    let currentRejectionReason = 'custom';
+    const rejectionTexts = {};
+    swh.webapp.showModalHtml('Reject origin save request ?', rejectModalHtml);
+    $('#swh-rejection-reason').on('change', (event) => {
+      // backup current textarea value
+      rejectionTexts[currentRejectionReason] = $('#swh-rejection-text').val();
+      currentRejectionReason = event.target.value;
+      let newRejectionText = '';
+      if (rejectionTexts.hasOwnProperty(currentRejectionReason)) {
+        // restore previous textarea value
+        newRejectionText = rejectionTexts[currentRejectionReason];
+      } else {
+        // fill textarea with default text according to rejection type
+        if (currentRejectionReason === 'invalid-origin') {
+          newRejectionText = `The origin with URL ${rowData['origin_url']} is not ` +
+            `a link to a  ${rowData['visit_type']} repository.`;
+        } else if (currentRejectionReason === 'invalid-origin-type') {
+          newRejectionText = `The origin with URL ${rowData['origin_url']} is not ` +
+            `of type ${rowData['visit_type']}.`;
+        } else if (currentRejectionReason === 'origin-not-found') {
+          newRejectionText = `The origin with URL ${rowData['origin_url']} cannot be found.`;
+        }
+      }
+      $('#swh-rejection-text').val(newRejectionText);
+    });
+    $('#swh-rejection-form').on('submit', (event) => {
+      event.preventDefault();
+      event.stopPropagation();
+      // ensure confirmation modal will be displayed above the html modal
+      $('#swh-web-modal-html').css('z-index', 4000);
+      swh.webapp.showModalConfirm(
+        'Reject origin save request ?',
+        'Are you sure to reject this origin save request ?',
+        rejectOriginSaveRequestCallback);
+    });
   }
 }
 
diff --git a/cypress/integration/admin.spec.js b/cypress/integration/admin.spec.js
--- a/cypress/integration/admin.spec.js
+++ b/cypress/integration/admin.spec.js
@@ -219,3 +219,48 @@
   });
 
 });
+
+describe('Test Admin Origin Save', function() {
+
+  it(`should reject a save code now request with note`, function() {
+    const originUrl = `https://example.org/${Date.now()}`;
+    const rejectionNote = 'The provided URL does not target a git repository.';
+
+    // anonymous user create request put in pending state
+    cy.visit(this.Urls.origin_save());
+
+    cy.get('#swh-input-origin-url')
+      .type(originUrl);
+
+    cy.get('#swh-input-origin-save-submit')
+      .click();
+
+    // admin user logs in and visit save code now admin page
+    cy.adminLogin();
+    cy.visit(this.Urls.admin_origin_save());
+
+    // admin rejects the save request and adds a rejection note
+    cy.contains('#swh-origin-save-pending-requests', originUrl)
+      .click();
+
+    cy.get('#swh-reject-save-origin-request')
+      .click();
+
+    cy.get('#swh-rejection-text')
+      .then(textarea => {
+        textarea.val(rejectionNote);
+      });
+
+    cy.get('#swh-rejection-submit')
+      .click();
+
+    cy.get('#swh-web-modal-confirm-ok-btn')
+      .click();
+
+    // checks rejection note has been saved to swh-web database
+    cy.request(this.Urls.api_1_save_origin('git', originUrl))
+      .then(response => {
+        expect(response.body[0]['note']).to.equal(rejectionNote);
+      });
+  });
+});
diff --git a/swh/web/common/origin_save.py b/swh/web/common/origin_save.py
--- a/swh/web/common/origin_save.py
+++ b/swh/web/common/origin_save.py
@@ -609,10 +609,16 @@
         task_ids.append(sor.loading_task_id)
     save_requests = []
     if task_ids:
-        tasks = scheduler().get_tasks(task_ids)
-        tasks = {task["id"]: task for task in tasks}
-        task_runs = scheduler().get_task_runs(tasks)
-        task_runs = {task_run["task"]: task_run for task_run in task_runs}
+        try:
+            tasks = scheduler().get_tasks(task_ids)
+            tasks = {task["id"]: task for task in tasks}
+            task_runs = scheduler().get_task_runs(tasks)
+            task_runs = {task_run["task"]: task_run for task_run in task_runs}
+        except Exception:
+            # allow to avoid mocking api GET responses for /origin/save endpoint when
+            # running cypress tests as scheduler is not available
+            tasks = {}
+            task_runs = {}
         for sor in requests_queryset:
             sr_dict = _update_save_request_info(
                 sor, tasks.get(sor.loading_task_id), task_runs.get(sor.loading_task_id),