files created with MT4 build 600 or higher (released after February 2014). Newer builds use a different compilation method that transforms logic into binary code rather than byte code, making full recovery practically impossible. Code Integrity
Instead of decompiling, consider these legitimate alternatives: ex4 to mq4 decompiler 40432 updatedl updated
If you want to use the trading signals from a locked EX4 indicator inside a new Expert Advisor, you do not need the source code. files created with MT4 build 600 or higher