SPIFFS_ERR_INDEX_REF_FREE (-10015) - help with understanding error

[pkourany]

I am running SPIFFS v3.7 with a Micron M25P128 (16MB) SPI flash chip. SPIFFS is configured as a SINGLETON with the following parameters:

 #define SPIFFS_CFG_PHYS_SZ(ignore)		(1024*1024*16)		// 16MB total arranged as 64 sectors x 256KB
 #define SPIFFS_CFG_PHYS_ERASE_SZ(ignore)	(256*1024)		// Erasable sector is 256KB
 #define SPIFFS_CFG_PHYS_ADDR(ignore)		(0)			// Start at address offset 0
 #define SPIFFS_CFG_LOG_PAGE_SZ(ignore)		(256)			// 256B page size (matches device page size)
 #define SPIFFS_CFG_LOG_BLOCK_SZ(ignore)	(256*1024)		// 256KB logical block size (matches physical sector size)

 #define LOG_PAGE_SIZE				256

u8_t spiffs_work_buf[LOG_PAGE_SIZE * 2];
u8_t spiffs_fds[32 * 8];
u8_t spiffs_cache_buf[(LOG_PAGE_SIZE + 32) * 8];

After some period of activity, SPIFFS issues a SPIFFS_ERR_INDEX_REF_FREE error. Can you please tell me what this error means and whether it is related to the configuration parameters? Where can I find a description of the other SPIFFS error codes?

Thanks!

[pkourany]

Anyone?