diff --git a/src/api/files.js b/src/api/files.js
index 971b056e..00d16339 100644
--- a/src/api/files.js
+++ b/src/api/files.js
@@ -94,6 +94,9 @@ export async function post (url, content = '', overwrite = false, onupload) {
       request.upload.onprogress = onupload
     }
 
+    // Send a message to user before closing the tab during file upload
+    window.onbeforeunload = () => "Files are being uploaded."
+
     request.onload = () => {
       if (request.status === 200) {
         resolve(request.responseText)
@@ -109,7 +112,8 @@ export async function post (url, content = '', overwrite = false, onupload) {
     }
 
     request.send(content)
-  })
+    // Upload is done no more message before closing the tab 
+  }).finally(() => { window.onbeforeunload = null })
 }
 
 function moveCopy (items, copy = false) {