Here you can find Excel File Extension Hardening. Cannot open externally generated xls file. solved how to fix the file format and extension of microsoft office excel document don t match the file could be corrupted or unsafe pupuweb. excel 2013 extension hardering. cannot turn off extension hardening in excel 2010. the file you are trying to open different format than specified the file extension when running standard reports to xls format using excel 2007 or later Related topic : Extension
Cannot Open Externally Generated Xls File
