After 7 days – the problem is solved and fixed!
After I upgraded Windows 7 to Windows 10, I started to use Metatrader. I created an expert advisor EA, and after compiling, I got: “ex4 write error”.
After that, I tried to compile many indicators and EAs, and all of them showed the same – ex4 write error.
What this means :
1) Your disk is full, and you can not write files. (in my case, I have 10GB free.)
2) Folder permission doesn’t allow writing. (in my case, everything is fine)
If you see that the MQL4 folder allows the system and administrator to write files, this is not a problem. You can check this if you press in Metatrader (mt4): File/Open File Folder, and then in MQL4 folder, you press Properties, then go to Security /Advanced and see write permissions.
3) Meta editor has a bug. (This is the problem in my case)
On November 12, Metatrader got a new version. 4.00 Build 910. In this version, the Meta editor has the problem of writing compiled files. It will be fixed in the next days, but meanwhile, you need to fix the problem.
Copy metaeditor.exe file from older version to new version. This is all !!!
In attach you can download the version which I use. This is only the metaeditor.exe file, which you need to copy into the installation folder.
Please check new versions of mt4 and mt5 and check the article about mt4 vs. mt5.