diff --git a/server/core/modulecmd.cc b/server/core/modulecmd.cc
index d8c96f55f..e2c3fab14 100644
--- a/server/core/modulecmd.cc
+++ b/server/core/modulecmd.cc
@@ -541,6 +541,12 @@ void modulecmd_arg_free(MODULECMD_ARG* arg)
     }
 }
 
+static void modulecmd_clear_error()
+{
+    prepare_error();
+    errbuf[0] = '\0';
+}
+
 bool modulecmd_call_command(const MODULECMD *cmd, const MODULECMD_ARG *args, json_t** output)
 {
     bool rval = false;
@@ -557,6 +563,8 @@ bool modulecmd_call_command(const MODULECMD *cmd, const MODULECMD_ARG *args, jso
             args = &MODULECMD_NO_ARGUMENTS;
         }
 
+        modulecmd_clear_error();
+
         json_t* discard = NULL;
         rval = cmd->func(args, output ? output : &discard);
         json_decref(discard);
@@ -575,12 +583,6 @@ void modulecmd_set_error(const char *format, ...)
     va_end(list);
 }
 
-static void modulecmd_clear_error()
-{
-    prepare_error();
-    errbuf[0] = '\0';
-}
-
 const char* modulecmd_get_error()
 {
     prepare_error();
diff --git a/server/modules/routing/debugcli/debugcmd.c b/server/modules/routing/debugcli/debugcmd.c
index ccbab6ecf..575173e1e 100644
--- a/server/modules/routing/debugcli/debugcmd.c
+++ b/server/modules/routing/debugcli/debugcmd.c
@@ -1679,13 +1679,23 @@ static void callModuleCommand(DCB *dcb, char *domain, char *id, char *v3,
         {
             json_t* output = NULL;
 
-            if (!modulecmd_call_command(cmd, arg, &output))
+            bool succeeded = modulecmd_call_command(cmd, arg, &output);
+
+            if (!succeeded && !output)
             {
-                const char* err = modulecmd_get_error();
-                dcb_printf(dcb, "Error: %s\n", *err ? err :
-                           "Call to module command failed, see log file for more details");
+                const char* s = modulecmd_get_error();
+                ss_dassert(s);
+
+                if (*s == 0)
+                {
+                    // No error had been set, so we add a default one.
+                    modulecmd_set_error("%s", "Call to module command failed, see log file for more details.");
+                }
+
+                output = modulecmd_get_json_error();
             }
-            else if (output)
+
+            if (output)
             {
                 char* js = json_dumps(output, JSON_INDENT(4));
                 dcb_printf(dcb, "%s\n", js);