diff --git a/engine-core/src/main/java/io/nosqlbench/engine/core/lifecycle/session/UnresolvedCommand.java b/engine-core/src/main/java/io/nosqlbench/engine/core/lifecycle/session/UnresolvedCommand.java
new file mode 100644
index 000000000..13e69bf67
--- /dev/null
+++ b/engine-core/src/main/java/io/nosqlbench/engine/core/lifecycle/session/UnresolvedCommand.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2024 nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.nosqlbench.engine.core.lifecycle.session;
+
+import io.nosqlbench.engine.cmdstream.Cmd;
+import scala.concurrent.impl.FutureConvertersImpl;
+
+public class UnresolvedCommand extends RuntimeException {
+    private final Cmd cmd;
+
+    public UnresolvedCommand(Cmd cmd, Throwable cause) {
+        super(cause);
+        this.cmd = cmd;
+    }
+
+    public String toString() {
+        final String helpmsg = """
+                Could not recognize command 'ARG'.
+                This means that all of the following searches for a compatible command failed:
+                1. commands: no scenario command named 'ARG' is known. (start, run, await, ...)
+                2. scripts: no auto script named './scripts/auto/ARG.js' in the local filesystem.
+                3. scripts: no auto script named 'scripts/auto/ARG.js' was found in the PROG binary.
+                4. workloads: no workload file named ARG[.yaml] was found in the local filesystem, even in include paths INCLUDES.
+                5. workloads: no workload file named ARG[.yaml] was bundled in PROG binary, even in include paths INCLUDES.
+                6. apps: no application named ARG was bundled in PROG.
+
+                You can discover available ways to invoke PROG by using the various --list-* commands:
+                [ --list-commands, --list-scripts, --list-workloads (and --list-scenarios), --list-apps ]
+                """
+            .replaceAll("ARG", getCmdName())
+            .replaceAll("PROG", "nb5");
+
+        return super.toString() + "\nadditional diagnostics:\n" + helpmsg;
+    }
+
+    private String getCmdName() {
+        String impl = cmd.getArgMap().get("_impl");
+        if (impl!=null) return impl;
+        return cmd.toString();
+    }
+
+}