diff -up stunnel-5.58/src/ctx.c.openssl30 stunnel-5.58/src/ctx.c
--- stunnel-5.58/src/ctx.c.openssl30	2021-07-28 11:12:05.743832246 +0200
+++ stunnel-5.58/src/ctx.c	2021-07-28 11:18:19.318021120 +0200
@@ -1015,6 +1015,15 @@ NOEXPORT int ui_retry() {
         default:
             return 0;
         }
+#ifdef ERR_LIB_OSSL_DECODER
+    case ERR_LIB_OSSL_DECODER:
+        switch(ERR_GET_REASON(err)) {
+        case ERR_R_UNSUPPORTED:
+            return 1;
+        default:
+            return 0;
+        }
+#endif
     case ERR_LIB_USER: /* PKCS#11 hacks */
         switch(ERR_GET_REASON(err)) {
         case 7UL: /* CKR_ARGUMENTS_BAD */