mcrypt_decrypt() error change key size

Question

mcrypt_decrypt(): Key of size 15 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported

How Can I fix this issue? my

Answer 1

Did you update to 5.6? It says

Invalid key and iv sizes are no longer accepted. mcrypt_decrypt() will now throw a warning and return FALSE if the inputs are invalid. Previously keys and IVs were padded with '\0' bytes to the next valid size.

Reference

Read the last line of that quote, and there you will find your solution :)

mcrypt_decrypt(): Key of size 15 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported

That means you need to pad your key with \0 (that's what previous versions were doing for you)

$key=$key."\0";