diff --git a/x-pack/plugins/enterprise_search/server/routes/workplace_search/oauth.ts b/x-pack/plugins/enterprise_search/server/routes/workplace_search/oauth.ts
index 5c2277278bb13..a87d22b6b047a 100644
--- a/x-pack/plugins/enterprise_search/server/routes/workplace_search/oauth.ts
+++ b/x-pack/plugins/enterprise_search/server/routes/workplace_search/oauth.ts
@@ -26,7 +26,7 @@ export function registerOAuthAuthorizeRoute({
           response_mode: schema.maybe(schema.string()),
           redirect_uri: schema.maybe(schema.string()),
           scope: schema.maybe(schema.string()),
-          state: schema.maybe(schema.string()),
+          state: schema.nullable(schema.string()),
         }),
       },
     },
@@ -49,7 +49,7 @@ export function registerOAuthAuthorizeAcceptRoute({
           response_type: schema.string(),
           redirect_uri: schema.maybe(schema.string()),
           scope: schema.maybe(schema.string()),
-          state: schema.maybe(schema.string()),
+          state: schema.nullable(schema.string()),
         }),
       },
     },
@@ -72,7 +72,7 @@ export function registerOAuthAuthorizeDenyRoute({
           response_type: schema.string(),
           redirect_uri: schema.maybe(schema.string()),
           scope: schema.maybe(schema.string()),
-          state: schema.maybe(schema.string()),
+          state: schema.nullable(schema.string()),
         }),
       },
     },