diff --git a/TeXmacs/tests/tmu/201_71.tmu b/TeXmacs/tests/tmu/201_71.tmu
new file mode 100644
index 0000000000..751d7d802b
--- /dev/null
+++ b/TeXmacs/tests/tmu/201_71.tmu
@@ -0,0 +1,18 @@
+<TMU|<tuple|1.1.0|2026.1.2>>
+
+<style|<tuple|generic|chinese|table-captions-above|number-europe|preview-ref>>
+
+<\body>
+  <\hide-preamble>
+    <assign|theorem|<with|color|<hybrid|backcolor>|>>
+  </hide-preamble>
+
+  1111
+</body>
+
+<\initial>
+  <\collection>
+    <associate|page-medium|paper>
+    <associate|page-screen-margin|false>
+  </collection>
+</initial>
diff --git a/devel/201_71.md b/devel/201_71.md
new file mode 100644
index 0000000000..97c9e5762f
--- /dev/null
+++ b/devel/201_71.md
@@ -0,0 +1,9 @@
+# [201_71] 修复导言区调用未定义的宏导致软件crash问题
+
+## 如何测试
+1. 打开 git/mogan/TeXmacs/tests/tmu/201_71.tmu 文件
+2. `Ctrl+Shift+p`进入导言区 
+3. 鼠标光标移动到`backcolor`后回车应该不会导致软件闪退问题
+
+
+
diff --git a/src/Typeset/Env/env_exec.cpp b/src/Typeset/Env/env_exec.cpp
index 285d78fd16..1075e93be3 100644
--- a/src/Typeset/Env/env_exec.cpp
+++ b/src/Typeset/Env/env_exec.cpp
@@ -560,6 +560,7 @@ edit_env_rep::exec (tree t) {
     return exec_frame_inverse (t);
 
   default:
+    if (L (t) == UNINIT) return t;
     if (L (t) < START_EXTENSIONS) {
       int i, n= N (t);
       // cout << "Executing " << t << "\n";
@@ -659,7 +660,7 @@ edit_env_rep::exec_with (tree t) {
     write_update (vars[i], newv[i]);
   tree r= exec (t[n - 1]);
   for (i= k - 1; i >= 0; i--)
-    write_update (vars[i], oldv[i]);
+    if (L (oldv[i]) != UNINIT) write_update (vars[i], oldv[i]);
 
   tree u (WITH, n);
   for (i= 0; i < k; i++) {
@@ -852,7 +853,11 @@ edit_env_rep::exec_value (tree t) {
   if (N (t) < 1) return tree (ERROR, "bad value");
   tree r= exec (t[0]);
   if (is_compound (r)) return tree (ERROR, "bad value");
-  return exec (read (r->label));
+  string name= r->label;
+  if (!provides (name)) return "";
+  tree value= read (name);
+  if (L (value) == UNINIT) return "";
+  return exec (value);
 }
 
 tree
@@ -2667,7 +2672,7 @@ edit_env_rep::exec_until_with (tree t, path p, string var, int level) {
     return true;
   }
   for (i= k - 1; i >= 0; i--)
-    write_update (vars[i], oldv[i]);
+    if (L (oldv[i]) != UNINIT) write_update (vars[i], oldv[i]);
   STACK_DELETE_ARRAY (vars);
   STACK_DELETE_ARRAY (oldv);
   STACK_DELETE_ARRAY (newv);