In attempting to perform steps in the kernel manual to create a configuration fragment using diffconfig, the task returns an error indicating that no configuration files exist when they do. 

Here are the steps to reproduce:

1. Have an existing build in ~/poky/build
2. cd ~/poky/build
3. bitbake linux-yocto -c kernel_configme -f
4. bitbake linux-yocto -c menuconfig

Step 4 invokes menuconfig.  Once menuconfig is running, make a minor change to the configuration and save the change and exit menuconfig

5. bitbake linux-yocto -c diffconfig

Step 5 returns errors.  See https://pastebin.com/7bpdLSJ0 for the console output.

=========================

output here if that is easier....


Loading cache: 100% |##################################################################| Time: 0:00:00
Loaded 1275 entries from dependency cache.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION        = "1.35.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "universal"
TARGET_SYS        = "i586-poky-linux"
MACHINE           = "qemux86"
DISTRO            = "poky"
DISTRO_VERSION    = "2.4"
TUNE_FEATURES     = "m32 i586"
TARGET_FPU        = ""
meta              
meta-poky         
meta-yocto-bsp    = "rocko:592c3449697ce39bf07864fafd7f0a61ca230561"
meta-mylayer      = "<unknown>:<unknown>"

WARNING: /home/scottrif/poky/meta/recipes-kernel/linux/linux-yocto_4.12.bb.do_kernel_configme is tainted from a forced run
Initialising tasks: 100% |#############################################################| Time: 0:00:00
NOTE: Executing SetScene Tasks
NOTE: Executing RunQueue Tasks
ERROR: linux-yocto-4.12.12+gitAUTOINC+eda4d18ce4_16de014967-r0 do_diffconfig: Error executing a python function in exec_python_func() autogenerated:

The stack trace of python calls that resulted in this exception/failure was:
File: 'exec_python_func() autogenerated', lineno: 2, function: <module>
     0001:
 *** 0002:do_diffconfig(d)
     0003:
File: '/home/scottrif/poky/meta/classes/cml1.bbclass', lineno: 66, function: do_diffconfig
     0062:        bb.fatal("No config files found. Did you do menuconfig ?\n%s" % e)
     0063:
     0064:    if isdiff:
     0065:        statement = 'diff --unchanged-line-format= --old-line-format= --new-line-format="%L" ' + configorig + ' ' + config + '>' + fragment
 *** 0066:        subprocess.check_call(statement, shell=True)
     0067:
     0068:        shutil.copy(configorig, config)
     0069:
     0070:        bb.plain("Config fragment has been dumped into:\n %s" % fragment)
File: '/usr/lib/python3.5/subprocess.py', lineno: 581, function: check_call
     0577:    if retcode:
     0578:        cmd = kwargs.get("args")
     0579:        if cmd is None:
     0580:            cmd = popenargs[0]
 *** 0581:        raise CalledProcessError(retcode, cmd)
     0582:    return 0
     0583:
     0584:
     0585:def check_output(*popenargs, timeout=None, **kwargs):
Exception: subprocess.CalledProcessError: Command 'diff --unchanged-line-format= --old-line-format= --new-line-format="%L" .config.orig .config>/home/scottrif/poky/build/tmp/work/qemux86-poky-linux/linux-yocto/4.12.12+gitAUTOINC+eda4d18ce4_16de014967-r0/fragment.cfg' returned non-zero exit status 1

ERROR: linux-yocto-4.12.12+gitAUTOINC+eda4d18ce4_16de014967-r0 do_diffconfig: Function failed: do_diffconfig
ERROR: Logfile of failure stored in: /home/scottrif/poky/build/tmp/work/qemux86-poky-linux/linux-yocto/4.12.12+gitAUTOINC+eda4d18ce4_16de014967-r0/temp/log.do_diffconfig.26418
ERROR: Task (/home/scottrif/poky/meta/recipes-kernel/linux/linux-yocto_4.12.bb:do_diffconfig) failed with exit code '1'
NOTE: Tasks Summary: Attempted 24 tasks of which 23 didn't need to be rerun and 1 failed.

Summary: 1 task failed:
  /home/scottrif/poky/meta/recipes-kernel/linux/linux-yocto_4.12.bb:do_diffconfig
Summary: There was 1 WARNING message shown.
Summary: There were 2 ERROR messages shown, returning a non-zero exit code.