If I add a Report Viewer to my asp.net web page, non master. upon debugging I get this error
Unhandled exception at line 15, column 16485 in http://localhost/SpecCenter/Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=RadScriptManager1_TSM&compress=1&_TSM_CombinedScripts_=;;System.Web.Extensions,+Version=4.0.0.0,+Culture=neutral,+PublicKeyToken=31bf3856ad364e35:en-US:6b5ccaa5-a290-46bd-afb1-b6039033842c:ea597d4b:b25378d2;Telerik.Web.UI:en-US:4b258e7c-7002-4d3e-9fa4-709d417eed98:16e4e7cd:f7645509:22a6274a:ed16cbdc:24ee1bba:c128760b:1e771326:88144a7a:8c2d243e:f46195d3:4cacbc31:dc752f02:58366029:4b09f651:ac926cdd:2003d0b8:2bef5fcc:a9b7ace7:6b3f73b3:e330518b:8e6f0d33:864068a5:6a6d718d:52af31a4:74603f77:6d43f6d9:78b9daca:8674cba1:7c926187:b7778d6c:c08e9f8a:59462f1:a51ee93e:19620875:874f8ea2:c172ae1e:9cdfc6e7:c8618e41:e4f8f289:1a73651d:16d8629e;System.Web.Extensions,+Version=4.0.0.0,+Culture=neutral,+PublicKeyToken=31bf3856ad364e35:en-US:6b5ccaa5-a290-46bd-afb1-b6039033842c:76254418
0x800a139e - JavaScript runtime error: Sys.WebForms.PageRequestManagerServerErrorException: Value cannot be null.
Parameter name: key
if I remove the report viewer the page loads and functions as expected.