The document summarizes an error that occurs when opening an XML map due to the "trimPcData" option not being selected by the user. This causes the "TrimPCData" value to be invalid, preventing the map from opening after it has been saved. The solution is to open the saved map source file in a text editor, search for the "TrimPCData" tag, and set its value to 0, 1, or 2 to respectively always trim whitespace, never trim whitespace, or use the trim setting from the properties. Additional troubleshooting links are provided.