diff --git a/dist/index.js b/dist/index.js
index d8f430f..7891726 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -647,8 +647,12 @@ function run() {
         catch (error) {
             core.debug(util_1.inspect(error));
             const message = error.message;
+            // Handle validation errors from workflow dispatch
             if (message == 'Unexpected inputs provided' ||
-                (message.startsWith('Required input') && message.endsWith('not provided'))) {
+                (message.startsWith('Required input') &&
+                    message.endsWith('not provided')) ||
+                message.startsWith('No ref found for:') ||
+                message == `Workflow does not have 'workflow_dispatch' trigger`) {
                 core.setOutput('error-message', message);
                 core.warning(message);
             }
diff --git a/docs/workflow-dispatch.md b/docs/workflow-dispatch.md
index 32376d7..a350075 100644
--- a/docs/workflow-dispatch.md
+++ b/docs/workflow-dispatch.md
@@ -97,6 +97,8 @@ When creating the [workflow_dispatch](https://docs.github.com/en/actions/referen
 
 - `Required input '...' not provided` - A required input for the workflow was not supplied as a named argument.
 - `Unexpected inputs provided` - Named arguments were supplied that are not defined as workflow inputs.
+- `No ref found for: ...` - The supplied `ref` does not exist in the target repository.
+- `Workflow does not have 'workflow_dispatch' trigger` - The target workflow doesn't define `on: workflow_dispatch`, OR, the supplied `ref` doesn't contain the target workflow.
 
 The `error-message` output can be used to provide feedback to the user as follows. Note that the action step needs an `id` to access outputs.
 
diff --git a/src/main.ts b/src/main.ts
index f507cf0..313c6d4 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -192,9 +192,13 @@ async function run(): Promise<void> {
   } catch (error) {
     core.debug(inspect(error))
     const message: string = error.message
+    // Handle validation errors from workflow dispatch
     if (
       message == 'Unexpected inputs provided' ||
-      (message.startsWith('Required input') && message.endsWith('not provided'))
+      (message.startsWith('Required input') &&
+        message.endsWith('not provided')) ||
+      message.startsWith('No ref found for:') ||
+      message == `Workflow does not have 'workflow_dispatch' trigger`
     ) {
       core.setOutput('error-message', message)
       core.warning(message)