diff --git a/docs/gen/ex_DIDNOTCONVERGE_msg.rst b/docs/gen/ex_DIDNOTCONVERGE_msg.rst
index f86acce02..4c2167bc6 100644
--- a/docs/gen/ex_DIDNOTCONVERGE_msg.rst
+++ b/docs/gen/ex_DIDNOTCONVERGE_msg.rst
@@ -2,4 +2,4 @@
 .. code-block::
 
    -V{t#,#}         'stl' region trigger index 0 is active: @([hybrid] a)
-   %Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
+   %Error-DIDNOTCONVERGE: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
diff --git a/docs/gen/ex_DIDNOTCONVERGE_nodbg_msg.rst b/docs/gen/ex_DIDNOTCONVERGE_nodbg_msg.rst
index 77abc8534..3ac0e9b0e 100644
--- a/docs/gen/ex_DIDNOTCONVERGE_nodbg_msg.rst
+++ b/docs/gen/ex_DIDNOTCONVERGE_nodbg_msg.rst
@@ -1,4 +1,4 @@
 .. comment: generated by t_lint_didnotconverge_nodbg_bad
 .. code-block::
 
-   %Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
+   %Error-DIDNOTCONVERGE: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
diff --git a/include/verilated.cpp b/include/verilated.cpp
index 64d5f6736..f3fce0a10 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -112,6 +112,36 @@ VerilatedContext* Verilated::s_lastContextp = nullptr;
 // Internal note: Globals may multi-construct, see verilated.cpp top.
 thread_local Verilated::ThreadLocal Verilated::t_s;
 
+//===========================================================================
+// Warning print helper
+
+void vl_print_warn_error(const char* prefix, const char* filename, int linenum,
+                         const char* msg) VL_MT_UNSAFE {
+    // A msg of "ERRORCODE: ..." is a code that changes to a prefix, e.g. "%Error-ERRORCODE: ..."
+    // This avoids changing public API of the vl_stop and related functions.
+    const char* msgNoCp = msg;
+    for (; isupper(*msgNoCp); ++msgNoCp);
+    if (msgNoCp[0] == ':' && msgNoCp[1] == ' ') {
+        const int codeWidth = static_cast<int>(msgNoCp - msg);
+        msgNoCp += 2;
+        if (filename && filename[0]) {
+            VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
+                "%s-%.*s: %s:%d: %s\n", prefix, codeWidth, msg, filename, linenum, msgNoCp);
+        } else {
+            VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
+                "%s-%.*s: %s\n", prefix, codeWidth, msg, msgNoCp);
+        }
+    } else {
+        if (filename && filename[0]) {
+            VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
+                "%s: %s:%d: %s\n", prefix, filename, linenum, msg);
+        } else {
+            VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
+                "%s: %s\n", prefix, msg);
+        }
+    }
+}
+
 //===========================================================================
 // User definable functions
 // Note a TODO is a future version of the API will pass a structure so that
@@ -119,8 +149,7 @@ thread_local Verilated::ThreadLocal Verilated::t_s;
 
 #ifndef VL_USER_FINISH  ///< Define this to override the vl_finish function
 void vl_finish(const char* filename, int linenum, const char* hier) VL_MT_UNSAFE {
-    // hier is unused in the default implementation.
-    (void)hier;
+    (void)hier;  // hier is unused in the default implementation.
     VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
         "- %s:%d: Verilog $finish\n", filename, linenum);
     Verilated::threadContextp()->gotFinish(true);
@@ -136,12 +165,7 @@ void vl_stop(const char* filename, int linenum, const char* hier) VL_MT_UNSAFE {
     if (Verilated::threadContextp()->fatalOnError()) {
         vl_fatal(filename, linenum, hier, msg);
     } else {
-        if (filename && filename[0]) {
-            // Not VL_PRINTF_MT, already on main thread
-            VL_PRINTF("%%Error: %s:%d: %s\n", filename, linenum, msg);
-        } else {
-            VL_PRINTF("%%Error: %s\n", msg);
-        }
+        vl_print_warn_error("%Error", filename, linenum, msg);
         Verilated::runFlushCallbacks();
     }
 }
@@ -149,16 +173,10 @@ void vl_stop(const char* filename, int linenum, const char* hier) VL_MT_UNSAFE {
 
 #ifndef VL_USER_FATAL  ///< Define this to override the vl_fatal function
 void vl_fatal(const char* filename, int linenum, const char* hier, const char* msg) VL_MT_UNSAFE {
-    // hier is unused in the default implementation.
-    (void)hier;
+    (void)hier;  // hier is unused in the default implementation.
     Verilated::threadContextp()->gotError(true);
     Verilated::threadContextp()->gotFinish(true);
-    if (filename && filename[0]) {
-        // Not VL_PRINTF_MT, already on main thread
-        VL_PRINTF("%%Error: %s:%d: %s\n", filename, linenum, msg);
-    } else {
-        VL_PRINTF("%%Error: %s\n", msg);
-    }
+    vl_print_warn_error("%Error", filename, linenum, msg);
     Verilated::runFlushCallbacks();
 
     VL_PRINTF("Aborting...\n");  // Not VL_PRINTF_MT, already on main thread
@@ -185,9 +203,8 @@ void vl_stop_maybe(const char* filename, int linenum, const char* hier, bool may
         && Verilated::threadContextp()->errorCount() < Verilated::threadContextp()->errorLimit()) {
         // Do just once when cross error limit
         if (Verilated::threadContextp()->errorCount() == 1) {
-            VL_PRINTF(  // Not VL_PRINTF_MT, already on main thread
-                "-Info: %s:%d: %s\n", filename, linenum,
-                "Verilog $stop, ignored due to +verilator+error+limit");
+            vl_print_warn_error("-Info", filename, linenum,
+                                "Verilog $stop, ignored due to +verilator+error+limit");
         }
     } else {
         vl_stop(filename, linenum, hier);
@@ -197,14 +214,8 @@ void vl_stop_maybe(const char* filename, int linenum, const char* hier, bool may
 
 #ifndef VL_USER_WARN  ///< Define this to override the vl_warn function
 void vl_warn(const char* filename, int linenum, const char* hier, const char* msg) VL_MT_UNSAFE {
-    // hier is unused in the default implementation.
-    (void)hier;
-    if (filename && filename[0]) {
-        // Not VL_PRINTF_MT, already on main thread
-        VL_PRINTF("%%Warning: %s:%d: %s\n", filename, linenum, msg);
-    } else {
-        VL_PRINTF("%%Warning: %s\n", msg);
-    }
+    (void)hier;  // hier is unused in the default implementation.
+    vl_print_warn_error("%Warning", filename, linenum, msg);
     Verilated::runFlushCallbacks();
 }
 #endif
diff --git a/src/V3SchedUtil.cpp b/src/V3SchedUtil.cpp
index f773070ea..eb7f6b4f8 100644
--- a/src/V3SchedUtil.cpp
+++ b/src/V3SchedUtil.cpp
@@ -96,8 +96,8 @@ AstNodeStmt* checkIterationLimit(AstNetlist* netlistp, const string& name, AstVa
     const std::string& file = VIdProtect::protect(locp->filename());
     const std::string& line = std::to_string(locp->lineno());
     stmtp->add("VL_FATAL_MT(\"" + V3OutFormatter::quoteNameControls(file) + "\", " + line
-               + ", \"\", \"" + name + " region did not converge after " + std::to_string(limit)
-               + " tries\");");
+               + ", \"\", \"DIDNOTCONVERGE: " + name + " region did not converge after "
+               + std::to_string(limit) + " tries\");");
     return ifp;
 }
 
diff --git a/test_regress/t/t_json_only_debugcheck.out b/test_regress/t/t_json_only_debugcheck.out
index bd6608cac..7f7c2b3a2 100644
--- a/test_regress/t/t_json_only_debugcheck.out
+++ b/test_regress/t/t_json_only_debugcheck.out
@@ -2707,7 +2707,7 @@
           ]},
           {"type":"CSTMT","name":"","addr":"(ONB)","loc":"a,0:0,0:0",
            "nodesp": [
-            {"type":"TEXT","name":"","addr":"(PNB)","loc":"a,0:0,0:0","text":"VL_FATAL_MT(\"t/t_enum_type_methods.v\", 11, \"\", \"NBA region did not converge after 100 tries\");"}
+            {"type":"TEXT","name":"","addr":"(PNB)","loc":"a,0:0,0:0","text":"VL_FATAL_MT(\"t/t_enum_type_methods.v\", 11, \"\", \"DIDNOTCONVERGE: NBA region did not converge after 100 tries\");"}
           ]}
         ],"elsesp": []},
         {"type":"ASSIGN","name":"","addr":"(QNB)","loc":"d,11:8,11:9","dtypep":"(R)",
@@ -2761,7 +2761,7 @@
             ]},
             {"type":"CSTMT","name":"","addr":"(LOB)","loc":"a,0:0,0:0",
              "nodesp": [
-              {"type":"TEXT","name":"","addr":"(MOB)","loc":"a,0:0,0:0","text":"VL_FATAL_MT(\"t/t_enum_type_methods.v\", 11, \"\", \"Active region did not converge after 100 tries\");"}
+              {"type":"TEXT","name":"","addr":"(MOB)","loc":"a,0:0,0:0","text":"VL_FATAL_MT(\"t/t_enum_type_methods.v\", 11, \"\", \"DIDNOTCONVERGE: Active region did not converge after 100 tries\");"}
             ]}
           ],"elsesp": []},
           {"type":"ASSIGN","name":"","addr":"(NOB)","loc":"d,11:8,11:9","dtypep":"(R)",
diff --git a/test_regress/t/t_lint_didnotconverge_bad.out b/test_regress/t/t_lint_didnotconverge_bad.out
index 5133d97c7..eced481cb 100644
--- a/test_regress/t/t_lint_didnotconverge_bad.out
+++ b/test_regress/t/t_lint_didnotconverge_bad.out
@@ -1,3 +1,3 @@
 -V{t#,#}         'stl' region trigger index 0 is active: @([hybrid] a)
-%Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
+%Error-DIDNOTCONVERGE: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
 Aborting...
diff --git a/test_regress/t/t_lint_didnotconverge_nodbg_bad.out b/test_regress/t/t_lint_didnotconverge_nodbg_bad.out
index 3eb3339bd..2567a6d55 100644
--- a/test_regress/t/t_lint_didnotconverge_nodbg_bad.out
+++ b/test_regress/t/t_lint_didnotconverge_nodbg_bad.out
@@ -1,2 +1,2 @@
-%Error: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
+%Error-DIDNOTCONVERGE: t/t_lint_didnotconverge_bad.v:7: Settle region did not converge after 100 tries
 Aborting...
diff --git a/test_regress/t/t_unopt_converge_initial_run_bad.out b/test_regress/t/t_unopt_converge_initial_run_bad.out
index 5c449acfb..ee51093f6 100644
--- a/test_regress/t/t_unopt_converge_initial_run_bad.out
+++ b/test_regress/t/t_unopt_converge_initial_run_bad.out
@@ -1,3 +1,3 @@
 -V{t#,#}         'stl' region trigger index 0 is active: @([hybrid] x)
-%Error: t/t_unopt_converge_initial.v:7: Settle region did not converge after 100 tries
+%Error-DIDNOTCONVERGE: t/t_unopt_converge_initial.v:7: Settle region did not converge after 100 tries
 Aborting...
diff --git a/test_regress/t/t_unopt_converge_ndbg_bad.out b/test_regress/t/t_unopt_converge_ndbg_bad.out
index d8b1afa04..bb60c4397 100644
--- a/test_regress/t/t_unopt_converge_ndbg_bad.out
+++ b/test_regress/t/t_unopt_converge_ndbg_bad.out
@@ -1,2 +1,2 @@
-%Error: t/t_unopt_converge.v:7: Settle region did not converge after 100 tries
+%Error-DIDNOTCONVERGE: t/t_unopt_converge.v:7: Settle region did not converge after 100 tries
 Aborting...
diff --git a/test_regress/t/t_unopt_converge_print_bad.out b/test_regress/t/t_unopt_converge_print_bad.out
index 29a108c3c..cb163e048 100644
--- a/test_regress/t/t_unopt_converge_print_bad.out
+++ b/test_regress/t/t_unopt_converge_print_bad.out
@@ -1,3 +1,3 @@
 -V{t#,#}         'stl' region trigger index 0 is active: @([hybrid] x)
-%Error: t/t_unopt_converge.v:7: Settle region did not converge after 100 tries
+%Error-DIDNOTCONVERGE: t/t_unopt_converge.v:7: Settle region did not converge after 100 tries
 Aborting...
diff --git a/test_regress/t/t_unopt_converge_run_bad.out b/test_regress/t/t_unopt_converge_run_bad.out
index aad3c80e0..1dfd9880f 100644
--- a/test_regress/t/t_unopt_converge_run_bad.out
+++ b/test_regress/t/t_unopt_converge_run_bad.out
@@ -1,3 +1,3 @@
 -V{t#,#}         'stl' region trigger index 0 is active: @([hybrid] x)
-%Error: t/t_unopt_converge.v:7: Settle region did not converge after 5 tries
+%Error-DIDNOTCONVERGE: t/t_unopt_converge.v:7: Settle region did not converge after 5 tries
 Aborting...