diff --git a/checkin_notes b/checkin_notes
index a637a58a68..44db9f4f56 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -7801,3 +7801,14 @@ David  17 Sept 2009
     generate_svn_version.sh
     sched/
         (most).cpp
+
+David  17 Sept 2009
+    - client: don't print error message if output file with <copy_file>
+        attribute is missing.  That's the app's problem, not BOINC's
+    - sample assimilator: if a canonical instance has no output files,
+        rather than quitting create a file named WU_NAME_no_output_files
+
+    client/
+        app_start.cpp
+    sched/
+        sample_assimilator.cpp
diff --git a/client/app_start.cpp b/client/app_start.cpp
index 8e0ae9facb..3599cafb84 100644
--- a/client/app_start.cpp
+++ b/client/app_start.cpp
@@ -339,12 +339,18 @@ int ACTIVE_TASK::copy_output_files() {
         sprintf(slotfile, "%s/%s", slot_dir, fref.open_name);
         get_pathname(fip, projfile, sizeof(projfile));
         int retval = boinc_rename(slotfile, projfile);
+#if 0
+        // this isn't a BOINC error.
+        // it just means the app didn't create an output file
+        // that it was supposed to.
+        //
         if (retval) {
             msg_printf(wup->project, MSG_INTERNAL_ERROR,
                 "Can't rename output file %s to %s: %s",
                 fip->name, projfile, boincerror(retval)
             );
         }
+#endif
     }
     return 0;
 }
diff --git a/sched/sample_assimilator.cpp b/sched/sample_assimilator.cpp
index ebe551e4a3..481e36d7d7 100644
--- a/sched/sample_assimilator.cpp
+++ b/sched/sample_assimilator.cpp
@@ -59,6 +59,7 @@ int assimilate_handler(
         const char *copy_path;
         get_output_file_infos(canonical_result, output_files);
         unsigned int n = output_files.size();
+        bool file_copied = false;
         for (i=0; i<n; i++) {
             FILE_INFO& fi = output_files[i];
             if (n==1) {
@@ -67,12 +68,17 @@ int assimilate_handler(
                 copy_path = config.project_path("sample_results/%s_%d", wu.name, i);
             }
             retval = boinc_copy(fi.path.c_str() , copy_path);
-            if (retval && !fi.optional) {
-                sprintf(buf, "couldn't copy file %s\n", fi.path.c_str());
-                write_error(buf);
-                return retval;
+            if (!retval) {
+                file_copied = true;
             }
         }
+        if (!file_copied) {
+            copy_path = config.project_path(
+                "sample_results/%s_%s", wu.name, "no_output_files"
+            );
+            FILE* f = fopen(copy_path, "w");
+            fclose(f);
+        }
     } else {
         sprintf(buf, "%s: 0x%x\n", wu.name, wu.error_mask);
         return write_error(buf);