If you truly need to recover a project or understand a strategy, there are safer paths than hunting for old decompilers:
When searching for "Full Version" or "Cracked" decompiler software, users face significant risks: Ex4 To Mq4 V4 Decompiler Version 4.0 5 Full Version
Most "Version 4.0.5" or "V4" decompilers you find online today are outdated. If you truly need to recover a project
Because this software sits in a legal "gray area," many downloads are injected with viruses or keyloggers designed to steal your trading account credentials. Here is everything you need to know about
However, finding a working version of this software in the current trading landscape is difficult. Here is everything you need to know about the state of decompilation for MetaTrader 4. What is an EX4 to MQ4 Decompiler?
Many sites claim to have a "Version 4.0.5" that works on modern builds, but after downloading, the software either doesn't run or produces "garbage" code that cannot be compiled.
The source code written in MQL4. This is readable and editable by humans.