Warning 'Packer returned 1, "..." might still be unpacked'
 

I'm using NSIS 3.01 on a Windows 10 System. I get the warning:

1 warning:
Packer returned 1, "C:\Users\TM\AppData\Local\Temp\exehead.tmp" might still be unpacked

The NSIS script never made Problems with NSIS 2.46, and I do not know what this message will exactly tells me. The installer itself is created and seems to work correctly.

Other Setup scritps does not return with this warning.

Any idea for this warning?

It would have been helpful if you showed us how you are using !packhdr.

The warning is new for v3 but the end result is unchanged.

If the child process started by !packhdr does not exit with error code 0 you will get this warning...

The !packhdr macro is not used in my script at all.

Of course it is, it is the only instruction that can generate that warning. Check the files you are !including...