ParserErrorException...

Problem

You get this error when running your application:

Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed.

file?username=ironspeed&id=470918

Application tracing is enabled

When application-level tracing is turned on, Response.Write is called to write diagnostic information which is not compatible with the smooth panel update feature (updatepanel).

Step 1:  Turn off application tracing (Build, Tracing and Event Logging…).

Step 2:  Re-build your application (Build, Rebuild All).

Step 3:  Run your application.

Conflicts with Smooth Panel Update

You may have a button, frequently the File Download button or File Upload button, inside a table panel or record panel which is surrounded by an UpdatePanel control.  In this case, the Ajax smooth panel update feature triggers an asynchronous postback and cannot recognize the file you are uploading or downloading.

To solve this problem, trigger a traditional postback when the button is clicked by setting the PostBack property for the button to ‘True’ in the Property Sheet.

See Also

Part IX:  Troubleshooting Applications

Application Will Not Run

Application Runs But No Data is Displayed

Application Error Messages