diff --git a/src/modules/host/handlers/Activity_Hub/OnBoarding/CreateNewActivity.ts b/src/modules/host/handlers/Activity_Hub/OnBoarding/CreateNewActivity.ts
index a119d1a..ec23d26 100644
--- a/src/modules/host/handlers/Activity_Hub/OnBoarding/CreateNewActivity.ts
+++ b/src/modules/host/handlers/Activity_Hub/OnBoarding/CreateNewActivity.ts
@@ -41,6 +41,25 @@ function normalizeJsonField(fields: any, key: string) {
   }
 }
 
+function sanitizeFileName(originalName: string): string {
+  const extIndex = originalName.lastIndexOf('.');
+  const extension =
+    extIndex !== -1 ? originalName.slice(extIndex).toLowerCase() : '';
+
+  const baseName =
+    extIndex !== -1 ? originalName.slice(0, extIndex) : originalName;
+
+  return (
+    baseName
+      .trim()
+      .replace(/\s+/g, '_')        // spaces → underscore
+      .replace(/[^a-zA-Z0-9_-]/g, '') // remove special chars
+      .toLowerCase() +
+    extension
+  );
+}
+
+
 /* -------------------------------- Handler -------------------------------- */
 
 export const handler = safeHandler(
@@ -109,7 +128,7 @@ export const handler = safeHandler(
             files.push({
               buffer: Buffer.concat(chunks),
               mimeType: mimeType || 'application/octet-stream',
-              fileName: filename || 'unknown',
+              fileName: sanitizeFileName(filename || 'unknown'),
               fieldName,
             });
           }