Sys.WebForms.PageRequestManagerParserErrorException: The message received
from the server could not be parsed. Common causes for this error are when the
response is modified by calls to Response.Write(), response filters, HttpModules,
or server trace is enabled.
Details: Error parsing near '
<!DOCTYPE html PUB'.
There are tons of references for this error message on the Web, but I can't figure it out. The problem is that the application works fine when I run it locally or when deployed to other servers. There is just one server where I get this error during a post back from an Update panel (it is supposed to populate and open a popup panel). There is no Response.Write() anywhere in the code and the other suggestions do not apply, either. I think. The next thing I will try is install the remote debugger. In the meantime, can someone tell me how to check if server trace is enabled (IIS 6)?