RESTEASY008200: JSON Binding deserialization error for valid JSON ----------------------------------------------------------------- Key: WFLY-10728 URL: https://issues.jboss.org/browse/WFLY-10728 Project: WildFly Issue Type: Bug Components: REST Affects Versions: 13.0.0.Final Environment: JDK-10.0.1 Reporter: Guido Schmidt Assignee: Ron Sigal Attachments: TestRestEasy.war, User.java, UserQueryForm.java, UsersApi.java, single-application.zip I found the following regression issue running the code inside an ejb jar: In the context of a search for a user for a user via the Wordpress REST API, I get e.g. following String: {code:JavaScript} {{[{ "id": 15, "username": "wpx1", "name": "Word Press1", "first_name": "Word", "last_name": "Press1", "email": &quot;wpx1(a)pb.com&quot;, "url": "", "description": "", "link": "http:\/\/www.pbpiazza.com\/dayc\/archives\/author\/wpx1", "locale": "en_US", "nickname": "wpx1", "slug": "wpx1", "roles": ["contributor"], "registered_date": "2018-07-23T08:59:13+00:00", "capabilities": { "edit_posts": true, "read": true, "level_1": true, "level_0": true, "delete_posts": true, "manage_bookings": true, "upload_event_images": true, "delete_events": true, "edit_events": true, "read_private_events": true, "delete_recurring_events": true, "edit_recurring_events": true, "edit_locations": true, "read_private_locations": true, "read_others_locations": true, "contributor": true }, "extra_capabilities": { "contributor": true }, "avatar_urls": { "24": "http:\/\/1.gravatar.com\/avatar\/a4d79ad5a72a13f7d7739c9a3dd9a17b?s=24&d=mm&r=g", "48": "http:\/\/1.gravatar.com\/avatar\/a4d79ad5a72a13f7d7739c9a3dd9a17b?s=48&d=mm&r=g", "96": "http:\/\/1.gravatar.com\/avatar\/a4d79ad5a72a13f7d7739c9a3dd9a17b?s=96&d=mm&r=g" }, "meta": [], "_links": { "self": [{ "href": "http:\/\/www.pbpiazza.com\/dayc\/wp-json\/wp\/v2\/users\/15" } ], "collection": [{ "href": "http:\/\/www.pbpiazza.com\/dayc\/wp-json\/wp\/v2\/users" } ] } } ]}} {code} This is achieved by a call of the UsersApi method listUsersAsString: ResteasyWebTarget target = (ResteasyWebTarget)restEasy.target(uri); target.proxy(UsersApi.class); The call rendering the result into a List<User> fails with error message in the subject. The result is perfectly fine running Wildfly 11.Plain test cases with Wildfly 13 libraries is also fine. It seems to be a runtime configuration issue of RESTEasy in WIldfly 13.