Index: ext/rbu/rbuvacuum.test
==================================================================
--- ext/rbu/rbuvacuum.test
+++ ext/rbu/rbuvacuum.test
@@ -296,10 +296,18 @@
 } {SQLITE_ERROR}
 do_test 2.1.2 {
   list [catch { rbu close } msg] $msg
 } {1 {SQLITE_ERROR - cannot vacuum wal mode database}}
 
+do_test 2.1.3 {
+  sqlite3rbu_vacuum rbu test.db state.db
+  rbu step
+} {SQLITE_ERROR}
+do_test 2.1.4 {
+  list [catch { rbu close_no_error } msg] $msg
+} {1 SQLITE_ERROR}
+
 reset_db
 do_execsql_test 2.2.0 {
   CREATE TABLE tx(a PRIMARY KEY, b BLOB);
   INSERT INTO tx VALUES(1, randomblob(900));
   INSERT INTO tx SELECT a+1, randomblob(900) FROM tx;

Index: ext/rbu/sqlite3rbu.c
==================================================================
--- ext/rbu/sqlite3rbu.c
+++ ext/rbu/sqlite3rbu.c
@@ -3785,11 +3785,15 @@
     sqlite3_free(p->aBuf);
     sqlite3_free(p->aFrame);
 
     rbuEditErrmsg(p);
     rc = p->rc;
-    *pzErrmsg = p->zErrmsg;
+    if( pzErrmsg ){
+      *pzErrmsg = p->zErrmsg;
+    }else{
+      sqlite3_free(p->zErrmsg);
+    }
     sqlite3_free(p->zState);
     sqlite3_free(p);
   }else{
     rc = SQLITE_NOMEM;
     *pzErrmsg = 0;

Index: ext/rbu/sqlite3rbu.h
==================================================================
--- ext/rbu/sqlite3rbu.h
+++ ext/rbu/sqlite3rbu.h
@@ -418,14 +418,14 @@
 ** as fully applied. Otherwise, assuming no error has occurred, save the
 ** current state of the RBU update appliation to the RBU database.
 **
 ** If an error has already occurred as part of an sqlite3rbu_step()
 ** or sqlite3rbu_open() call, or if one occurs within this function, an
-** SQLite error code is returned. Additionally, *pzErrmsg may be set to
-** point to a buffer containing a utf-8 formatted English language error
-** message. It is the responsibility of the caller to eventually free any 
-** such buffer using sqlite3_free().
+** SQLite error code is returned. Additionally, if pzErrmsg is not NULL,
+** *pzErrmsg may be set to point to a buffer containing a utf-8 formatted
+** English language error message. It is the responsibility of the caller to
+** eventually free any such buffer using sqlite3_free().
 **
 ** Otherwise, if no error occurs, this function returns SQLITE_OK if the
 ** update has been partially applied, or SQLITE_DONE if it has been 
 ** completely applied.
 */

Index: ext/rbu/test_rbu.c
==================================================================
--- ext/rbu/test_rbu.c
+++ ext/rbu/test_rbu.c
@@ -76,10 +76,11 @@
     {"dbMain_eval", 3, "SQL"},    /* 4 */
     {"bp_progress", 2, ""},       /* 5 */
     {"db", 3, "RBU"},             /* 6 */
     {"state", 2, ""},             /* 7 */
     {"progress", 2, ""},          /* 8 */
+    {"close_no_error", 2, ""},    /* 9 */
     {0,0,0}
   };
   int iCmd;
 
   if( objc<2 ){
@@ -100,15 +101,20 @@
       int rc = sqlite3rbu_step(pRbu);
       Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
       break;
     }
 
+    case 9: /* close_no_error */ 
     case 1: /* close */ {
       char *zErrmsg = 0;
       int rc;
       Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
-      rc = sqlite3rbu_close(pRbu, &zErrmsg);
+      if( iCmd==1 ){
+        rc = sqlite3rbu_close(pRbu, &zErrmsg);
+      }else{
+        rc = sqlite3rbu_close(pRbu, 0);
+      }
       if( rc==SQLITE_OK || rc==SQLITE_DONE ){
         Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
         assert( zErrmsg==0 );
       }else{
         Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));