diff --git a/test/integration/reorganize_pages_spec.mjs b/test/integration/reorganize_pages_spec.mjs
index 389a69f3602c5..b0f03231c547f 100644
--- a/test/integration/reorganize_pages_spec.mjs
+++ b/test/integration/reorganize_pages_spec.mjs
@@ -190,13 +190,12 @@ describe("Reorganize Pages View", () => {
               return false;
             }
           );
-          const dndPromise = dragAndDrop(
+          await dragAndDrop(
             page,
             getThumbnailSelector(1),
             [[0, rect2.y - rect1.y + rect2.height / 2]],
             10
           );
-          await dndPromise;
           await awaitPromise(handleAddedMarker);
           await awaitPromise(handleRemovedMarker);
         })
@@ -1639,4 +1638,66 @@ describe("Reorganize Pages View", () => {
       );
     });
   });
+
+  describe("Dragging mustn't be possible when pasting (bug 2021934)", () => {
+    let pages;
+
+    beforeEach(async () => {
+      pages = await loadAndWait(
+        "page_with_number.pdf",
+        "#viewsManagerToggleButton",
+        "page-fit",
+        null,
+        { enableSplitMerge: true }
+      );
+    });
+
+    afterEach(async () => {
+      await closePages(pages);
+    });
+
+    it("should check that dragging is disabled when pasting", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await waitForThumbnailVisible(page, 1);
+
+          await Promise.all([
+            page.waitForSelector(`#thumbnailsView.isDragging`, {
+              visible: true,
+            }),
+            dragAndDrop(page, getThumbnailSelector(1), [[0, 10]], 10),
+          ]);
+
+          await page.waitForSelector(`#thumbnailsView.isDragging`, {
+            hidden: true,
+          });
+          await waitAndClick(
+            page,
+            `.thumbnail:has(${getThumbnailSelector(1)}) input`
+          );
+          await waitAndClick(page, "#viewsManagerStatusActionButton");
+          await waitAndClick(page, "#viewsManagerStatusActionCopy");
+
+          // If dragging isn't disabled, the promise will resolve with the
+          // selector. Otherwise, it will resolve with undefined (dragAndDrop
+          // has no return), which is the expected behavior.
+          const abortController = new AbortController();
+          const first = await Promise.race([
+            page.waitForSelector(`#thumbnailsView.isDragging`, {
+              visible: true,
+              signal: abortController.signal,
+            }),
+            dragAndDrop(page, getThumbnailSelector(1), [[0, 10]], 10),
+          ]);
+          abortController.abort();
+
+          expect(first)
+            .withContext(
+              `In ${browserName}, dragging should be disabled when pasting`
+            )
+            .toBeUndefined();
+        })
+      );
+    });
+  });
 });
diff --git a/web/pdf_thumbnail_viewer.js b/web/pdf_thumbnail_viewer.js
index 8ee1cb29473f4..734684bffa34a 100644
--- a/web/pdf_thumbnail_viewer.js
+++ b/web/pdf_thumbnail_viewer.js
@@ -159,6 +159,8 @@ class PDFThumbnailViewer {
 
   #undoCloseButton = null;
 
+  #isInPasteMode = false;
+
   /**
    * @param {PDFThumbnailViewerOptions} options
    */
@@ -525,6 +527,7 @@ class PDFThumbnailViewer {
   }
 
   #updateThumbnails(currentPageNumber) {
+    this.#resetCurrentThumbnail(0);
     let newCurrentPageNumber = 0;
     const pagesMapper = this.#pagesMapper;
     const prevThumbnails = (this.#savedThumbnails = this._thumbnails);
@@ -658,13 +661,13 @@ class PDFThumbnailViewer {
       const newIndex = lastDraggedOverIndex + 1;
       const pagesToMove = Array.from(selectedPages).sort((a, b) => a - b);
       const pagesMapper = this.#pagesMapper;
-      let currentPageNumber = isNaN(this.#pageNumberToRemove)
+      const currentPageNumber = isNaN(this.#pageNumberToRemove)
         ? pagesToMove[0]
         : this.#pageNumberToRemove;
 
       pagesMapper.movePages(selectedPages, pagesToMove, newIndex);
 
-      currentPageNumber = this.#updateThumbnails(currentPageNumber);
+      this.#updateCurrentPage(this.#updateThumbnails(currentPageNumber));
       this.#computeThumbnailsPosition();
 
       selectedPages.clear();
@@ -676,8 +679,6 @@ class PDFThumbnailViewer {
         pagesMapper,
         type: "move",
       });
-
-      this.#updateCurrentPage(currentPageNumber);
     }
 
     if (!isNaN(this.#pageNumberToRemove)) {
@@ -695,7 +696,6 @@ class PDFThumbnailViewer {
 
   #updateCurrentPage(currentPageNumber) {
     setTimeout(() => {
-      this.#resetCurrentThumbnail(0);
       this.forceRendering();
       const newPageNumber = currentPageNumber || 1;
       this.linkService.goToPage(newPageNumber);
@@ -765,6 +765,7 @@ class PDFThumbnailViewer {
   }
 
   #togglePasteMode(enable) {
+    this.#isInPasteMode = enable;
     if (enable) {
       this.container.classList.add("pasteMode");
       for (const thumbnail of this._thumbnails) {
@@ -822,14 +823,14 @@ class PDFThumbnailViewer {
     this.#toggleMenuEntries(true);
 
     const pagesMapper = this.#pagesMapper;
-    let currentPageNumber = this.#copiedPageNumbers.includes(
+    const currentPageNumber = this.#copiedPageNumbers.includes(
       this._currentPageNumber
     )
       ? 0
       : this._currentPageNumber;
 
     pagesMapper.pastePages(index);
-    currentPageNumber = this.#updateThumbnails(currentPageNumber);
+    this.#updateCurrentPage(this.#updateThumbnails(currentPageNumber));
 
     this.eventBus.dispatch("pagesedited", {
       source: this,
@@ -842,8 +843,6 @@ class PDFThumbnailViewer {
     this.#isCut = false;
     this.#updateMenuEntries();
     this.#updateStatus("select");
-
-    this.#updateCurrentPage(currentPageNumber);
   }
 
   #deletePages(type = "delete") {
@@ -855,7 +854,7 @@ class PDFThumbnailViewer {
       this.#updateStatus("delete");
     }
     const pagesMapper = this.#pagesMapper;
-    let currentPageNumber = selectedPages.has(this._currentPageNumber)
+    const currentPageNumber = selectedPages.has(this._currentPageNumber)
       ? 0
       : this._currentPageNumber;
     const pagesToDelete = (this.#deletedPageNumbers = Uint32Array.from(
@@ -863,7 +862,7 @@ class PDFThumbnailViewer {
     ).sort((a, b) => a - b));
 
     pagesMapper.deletePages(pagesToDelete);
-    currentPageNumber = this.#updateThumbnails(currentPageNumber);
+    this.#updateCurrentPage(this.#updateThumbnails(currentPageNumber));
     selectedPages.clear();
     this.#updateMenuEntries();
 
@@ -873,8 +872,6 @@ class PDFThumbnailViewer {
       pageNumbers: pagesToDelete,
       type,
     });
-
-    this.#updateCurrentPage(currentPageNumber);
   }
 
   #updateMenuEntries() {
@@ -1224,7 +1221,7 @@ class PDFThumbnailViewer {
       } = e;
       if (
         e.button !== 0 || // Skip right click.
-        this.#pagesMapper.copiedPageNumbers?.length > 0 ||
+        this.#isInPasteMode ||
         !isNaN(this.#lastDraggedOverIndex) ||
         !draggedImage.classList.contains("thumbnailImageContainer")
       ) {