You should pass in .dsc file, not .dec file for -p  option of build.

Mike

From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of np l
Sent: Saturday, July 30, 2022 7:02 PM
To: devel@edk2.groups.io
Subject: [edk2-devel] EDK2 build error:Unknown fatal error when processing []

Hi,
I got a fatal error with a command "build -p edk2\MdeModulePkg\MdeModulePkg.dec -a X64 -t VS2015x86".
(Python version is  2.7.15.Build tool is VS2015x86)
   But  UEFI\edk2\EmulatorPkg\EmulatorPkg.dec can be build successfully.
   I have update edk2 with "git pull" but the same error occured.
   I also test it in another laptop with python  version 3.9.9 build tool VS2019,a same error occur.

What should I do?

error log as blow:
[cid:image001.png@01D8A452.30118E00]

Thanks!