It seams that your site does not register FormsMvcRouteHandler correctly. Do you have custom code to modify default MvcRouteHandler or something similar?
Fixed! Had an error on the submit button, somehow i removed classes and scripts.
thanx for your input
Getting this error when submitting:
GET http://mysite/EPiServer.Forms/DataSubmit/Submit?[object%20FormData]&_=1517839379790 404 (Not Found)
and this
WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:4 Uncaught ReferenceError: returnedResult is not defined (WebResource.axd?d=TzRGlCddaaqtz0Im2nSJhAXdG23Gs7DIWCwdyo5-09SR9iM5DxmKEtLgareVliM-zH2zNm1dKyr_Szksy5fj3SNh0afChBTlB5cs3UrXoR64cfpawdBk9-2NGLcKVRRLbnS1fP2VeQaj_O4LjiOGm0Sp1AbTlBteLbMDZDfBWwE1&t=636440926540000000:1) (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:2)
at Object.error (WebResource.axd?d=TzRGlCddaaqtz0Im2nSJhAXdG23Gs7DIWCwdyo5-09SR9iM5DxmKEtLgareVliM-zH2zNm1dKyr_Szksy5fj3SNh0afChBTlB5cs3UrXoR64cfpawdBk9-2NGLcKVRRLbnS1fP2VeQaj_O4LjiOGm0Sp1AbTlBteLbMDZDfBWwE1&t=636440926540000000:1)
at i (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:2)
at Object.fireWith [as rejectWith] (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:2)
at y (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:4)
at c (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:4)
at Object.send (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:4)
at Function.ajax (WebResource.axd?d=rQapnFTl_pgMjn3yGS-nPv0RTkWSSdthN4fmJQkvR675GTX0mow4bwxt1YoF3gsg8vvJd8cPSbzsK6kxK0qTsoAesqQpSNPv-eNEpSmOhm8_0y3srp_GFK7Db-fkiIFCxYEJK45YxxrwbhA88QwNIkE-QMxoIc6A-u_49ygXWHk1&t=636440926540000000:4)
at b (WebResource.axd?d=TzRGlCddaaqtz0Im2nSJhAXdG23Gs7DIWCwdyo5-09SR9iM5DxmKEtLgareVliM-zH2zNm1dKyr_Szksy5fj3SNh0afChBTlB5cs3UrXoR64cfpawdBk9-2NGLcKVRRLbnS1fP2VeQaj_O4LjiOGm0Sp1AbTlBteLbMDZDfBWwE1&t=636440926540000000:1)
at Object.
at Object.