Whenever a common dialog box function fails, an application can call the CommDlgExtendedError function to find out the cause of the failure. The CommDlgExtendedError function returns an error value that identifies the cause of the most recent error.
Six constants are defined in the CDERR.H header file that identify the ranges of error values for categories of errors returned by CommDlgExtendedError. Following are these constants in ascending order by value range:
| Constant | Meaning |
| CDERR_GENERALCODES | General error codes for common dialog boxes. These errors are in the range 0x0000 through 0x0FFF. |
| PDERR_PRINTERCODES | Error codes for the Print common dialog box. These errors are in the range 0x1000 through 0x1FFF. |
| CFERR_CHOOSEFONTCODES | Error codes for the Font common dialog box. These errors are in the range 0x2000 through 0x2FFF. |
| FNERR_FILENAMECODES | Error codes for the Open and Save As common dialog boxes. These errors are in the range 0x3000 through 0x3FFF. |
| FRERR_FINDREPLACECODES | Error codes for the Find and Replace common dialog boxes. These errors are in the range 0x4000 through 0x4FFF. |
| CCERR_CHOOSECOLORCODES | Error codes for the Color common dialog box. These errors are in the range 0x5000 through 0x5FFF. |