Ioncube is a PHP encoder that compiles PHP source code into a binary format (bytecode) that can only be executed by the Ioncube Loader – a PHP extension. The original source code is not present in plain text, making it difficult (though not impossible) to reverse-engineer.
If you are seeing errors such as "The file encoded as type [1/74] cannot be decoded," it usually indicates an infrastructure issue rather than a need for a "decoder" tool: