While updating the payroll or maintenance in the QuickBooks application you might come across QuickBooks error 15215. It simply states unable to verify the digital signature and suggests a solution to clean all the junk files with the disk cleanup. Following are key steps that you must take to eliminate error 15215 in QuickBooks. First of all, you must try to restart your system and run QuickBooks as a windows administrator. The next step should be to verify that Use TLS 1 .0 is checked while TLS 1.1 and TLS 1.2 are unchecked in the Internet Options window. Restarting the windows in selective startup mode also could be the best way to deal with error 15215. In case you are not able to tackle the problem then you must connect with us on the QuickBooks support number.