GWT-RPC responses have a string table to deduplicate strings and minimize the response size. When deserializing a server response the code will try to lookup a type signature string in the string table, however in your case the lookup returns wrong data and serialization fails. "153221" is not a type signature but some other data you have transferred, maybe a variable value.
Usually it means your GWT versions are out of sync. Make double sure to deploy the gwt-servlet.jar from GWT 2.8.2 and not the one of GWT 2.6.1 to your server. Then make double sure you are actually compile your app with GWT 2.8.2 and not with 2.6.1. -- J. -- You received this message because you are subscribed to the Google Groups "GWT Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit+unsubscr...@googlegroups.com. To post to this group, send email to email@example.com. Visit this group at https://groups.google.com/group/google-web-toolkit. For more options, visit https://groups.google.com/d/optout.