diff --git a/copyparty/web/up2k.js b/copyparty/web/up2k.js
index 4ee0883a..28146593 100644
--- a/copyparty/web/up2k.js
+++ b/copyparty/web/up2k.js
@@ -998,6 +998,14 @@ function up2k_init(subtle) {
             });
     }
 
+    function unqueue_up(t) {
+        t.postlist = [];
+        var arr = st.todo.upload;
+        for (var a = arr.length - 1; a >= 0; a--)
+            if (arr[a].nfile == t.n)
+                arr.splice(a, 1);
+    }
+
     var pvis = new U2pvis("bz", '#u2cards', uc, st),
         donut = new Donut(uc, st);
 
@@ -2631,7 +2639,7 @@ function up2k_init(subtle) {
                     cbd.push(a == cdr_idx ? cdr_sz : chunksize);
                 }
 
-                t.postlist = [];
+                unqueue_up(t);
                 t.wark = response.wark;
                 var missing = response.hash;
                 for (var a = 0; a < missing.length; a++) {
@@ -2920,8 +2928,7 @@ function up2k_init(subtle) {
             var txt = unpre((xhr.response && xhr.response.err) || xhr.responseText);
             if (txt.indexOf('upload blocked by x') + 1) {
                 apop(st.busy.upload, upt);
-                for (var a = pcar; a <= pcdr; a++)
-                    apop(t.postlist, a);
+                unqueue_up(t);
                 pvis.seth(t.n, 1, "ERROR");
                 pvis.seth(t.n, 2, txt.split(/\n/)[0]);
                 pvis.move(t.n, 'ng');
@@ -2944,8 +2951,10 @@ function up2k_init(subtle) {
                 st.etac.u++;
                 st.etac.t++;
             }
-            else if (txt.indexOf('already got that') + 1 ||
-                txt.indexOf('already being written') + 1) {
+            else if (txt.indexOf('already got that') + 1) {
+                unqueue_up(t);
+            }
+            else if (txt.indexOf('already being written') + 1) {
                 t.nojoin = t.nojoin || t.postlist.length;
                 console.log("ignoring dupe-segment with backoff", t.nojoin, t.name, t);
                 if (!toast.visible && st.todo.upload.length < 4)
@@ -2953,6 +2962,10 @@ function up2k_init(subtle) {
             }
             else {
                 xhrchk(xhr, L.u_cuerr2.format(snpart, Math.ceil(t.size / chunksize), esc(t.name)), "404, target folder not found (???)", "warn", t);
+                if (txt.indexOf('unknown wark') == 0) {
+                    t.cooldown = t.coolmul = 0;
+                    unqueue_up(t);
+                }
                 chill(t);
             }
             orz2(xhr);
@@ -2963,8 +2976,10 @@ function up2k_init(subtle) {
                 apop(t.postlist, a);
             if (!t.postlist.length) {
                 t.t_uploaded = Date.now();
-                pvis.seth(t.n, 1, 'verifying');
-                st.todo.handshake.unshift(t);
+                if (!has(st.busy.handshake, t)) {
+                    pvis.seth(t.n, 1, 'verifying');
+                    st.todo.handshake.unshift(t);
+                }
             }
             tasker();
         }
@@ -2999,6 +3014,7 @@ function up2k_init(subtle) {
                 if (!toast.visible)
                     toast.warn(9.98, L.u_cuerr.format(snpart, Math.ceil(t.size / chunksize), esc(t.name)), t);
 
+                unqueue_up(t);  // maybe unknown wark (ff drops undrained rsp)
                 t.nojoin = t.nojoin || t.postlist.length;  // maybe rproxy postsize limit
                 console.log('chunkpit onerror,', t.name, t);
                 orz2(xhr);