1. IonCube V10.x is modern. PHP 5.6 is dead. PHP 5.6 reached End of Life (EOL) over 7 years ago. IonCube V10.x was designed for PHP 7.0+. While the Loader might work on 5.6, the encoder (V10) expects modern crypto libraries. If someone sold you PHP 5.6 code encoded with IonCube V10, they made a strange technical choice.
2. The "Decoders" online are scams. Searching for "Ioncube Decoder V10.x Php 5.6" leads to: ---- Ioncube Decoder V10.x Php 5.6
If you encoded the files yourself but lost the original source, IonCube Ltd. may help – provided you can prove ownership (e.g., original encoder purchase receipt, private key). They do not offer a public decoder, but for lost keys, they have recovery procedures. If someone sold you PHP 5
If you own the code but lost the source, or you are trying to recover a legacy project, here is the reality path: original encoder purchase receipt
IonCube is a PHP encoder and loader. It compiles PHP source code into a proprietary intermediate bytecode, which is then stored in encoded files (usually .inc.php or .php). To run these files, a server needs the IonCube Loader – a PHP extension that decrypts and executes the code on the fly.