diff --git a/x-pack/legacy/plugins/reporting/config.ts b/x-pack/legacy/plugins/reporting/config.ts
index 34fc1f452fbc0..68185b29ff2f7 100644
--- a/x-pack/legacy/plugins/reporting/config.ts
+++ b/x-pack/legacy/plugins/reporting/config.ts
@@ -140,7 +140,9 @@ export async function config(Joi: any) {
     }).default(),
     encryptionKey: Joi.when(Joi.ref('$dist'), {
       is: true,
-      then: Joi.string(),
+      then: Joi.string()
+        .allow(null)
+        .default(null),
       otherwise: Joi.string().default('a'.repeat(32)),
     }),
     roles: Joi.object({