All of a sudden, I am getting the error show below. It is poping up a LOT when making changes to core modules (in the "settings" page, not changing code) or adding/copying a page. When I press "Update" the error pops up.
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 '
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