# Return Code of the File Functions

On the FatFs API, most of file functions return common result code as enum type `FRESULT`. When a function succeeded, it returns zero, otherwise returns non-zero value that indicates type of error.

FR_OK (0)
  The function succeeded.
FR_DISK_ERR
  An unrecoverable error occured in the lower layer, `disk_read()`, `disk_write()` or `disk_ioctl()` function.
FR_INT_ERR
  Assertion failed. An insanity is detected in the internal process. One of the following possibilities are suspected.
  - There is any error of the FAT structure on the volume.
  - Work area (file system object, file object or etc...) is broken by stack overflow or any other application. This is the reason in most case.
  - An `FR_DISK_ERR` has occured on the file object.
FR_NOT_READY
  The disk drive cannot work due to incorrect medium removal or `disk_initialize()` function failed.
FR_NO_FILE
  Could not find the file.
FR_NO_PATH
  Could not find the path.
FR_INVALID_NAME
  The given string is invalid as the path name.
FR_DENIED
  The required access was denied due to one of the following reasons:
  - Write mode open against the read-only file.
  - Deleting the read-only file or directory.
  - Deleting the non-empty directory or current directory.
  - Reading the file opened without `FA_READ` flag.
  - Any modification to the file opened without `FA_WRITE` flag.
  - Could not create the file or directory due to the directory table is full.
  - Could not create the directory due to the volume is full.
FR_EXIST
  Any file or directory that has the same name is already existing.
FR_INVALID_OBJECT
  The file/directory object is invalid or a null pointer is given.
FR_WRITE_PROTECTED
  Any write mode action against the write-protected media.
FR_INVALID_DRIVE
  Invalid drive number is specified. (Related option: `_VOLUMES`)
FR_NOT_ENABLED
  Work area for the logical drive has not been registered by `f_mount()` function.
FR_NO_FILESYSTEM
  There is no valid FAT volume on the drive.
FR_MKFS_ABORTED
  The `f_mkfs()` function aborted before start in format due to a reason as follows:
  - The disk size is too small.
  - Not allowable cluster size for this disk. This can occure when number of clusters gets near the 0xFF7 and 0xFFF7.
  - There is no partition related to the logical drive. (Related option: `_MULTI_PARTITION`)
FR_TIMEOUT
  The function canceled due to a timeout of thread-safe control. (Related option: `_TIMEOUT`)
FR_LOCKED
  The file access is rejected by file sharing control. (Related option: `_FS_LOCK`)
FR_NOT_ENOUGH_CORE
  Not enough memory for the operation. There is one of the following reasons:
  - Could not allocate a memory for LFN working buffer. (Related option: `_USE_LFN`)
  - Given CLMT is insufficient size for the required size.
FR_TOO_MANY_OPEN_FILES
  Number of open files has been reached maximum value and no more file can be opened. (Related option: `_FS_LOCK`)
FR_INVALID_PARAMETER
  The given parameter is invalid or there is any inconsistent.