Beware that on some versions of PHP, the PHP session ID value is a hexadecimal hash but on some newer systems the configuration is used to adjust the contents of the session ID string:

; Define how many bits are stored in each character when converting
; the binary hash data to something readable.
;
; 4 bits: 0-9, a-f
; 5 bits: 0-9, a-v
; 6 bits: 0-9, a-z, A-Z, "-", ","
session.hash_bits_per_character = 5