only work on files compiled with MT4 Build 509 or lower (pre-2014). Modern Encryption
: Many "free decompiler" downloads contain high-threat malware (e.g., JboxGeneric) that can steal your trading credentials or personal data.
If the .ex4 came from your own code and you lost the .mq4 , you cannot recover it. If it's from a third party, you must request the original .mq4 from the author.
: Even when conversion "works," the resulting MQ4 file often lacks original variable names, comments, and logical structures, producing broken or heavily obfuscated code that requires extensive manual debugging. Risks of "Free Online" Tools
If you need the source code of an indicator or Expert Advisor (EA), consider these legitimate paths: Contact the Developer
Specialists use high-end tools like or Ghidra to manually reconstruct code at the processor level.
Understanding MetaQuotes security updates reveals why these automated tools fail, why downloadable decompilers are highly risky, and how you can actually recover your source code safely. Why Automated EX4 to MQ4 Online Converters Fail
Be cautious when using free "EX4-to-MQ4-decompiler.exe" tools found online.
Store complete copies of your source code on a dedicated external hard drive or flash drive kept entirely offline. To help you move forward safely, tell me:
Meaningful names like Lotsize or StopLoss will be replaced with generic tags like g_var_128 or d_input_12 .
Check the Logs and Projects folders to see if a previous version of your .mq4 file is cached. 2. Hire a Professional Reverse Engineer
[Lost MQ4 Source Code] │ ┌──────────────────┼──────────────────┐ ▼ ▼ ▼ [Contact Original] [Reconstruct Logic] [Hire Verified] [Developer] [From Settings] [MQL5 Freelance] 1. Contact the Original Developer
To advance your project safely, consider how you want to handle your file logic. Here are a few specific ways to proceed: