Trying to setup my dev environment to play around with SPFx and ran into this error:

[08:33:19] Error - [trust-cert] Error: root "Trusted Root Certification Authorities"
Signature matches Public Key
CertUtil: -addstore command FAILED: 0x80070005 (WIN32: 5 ERROR_ACCESS_DENIED)
CertUtil: Access is denied.

[08:33:19] Error – [trust-cert] Certificate trust failed with an unknown error.
[08:33:19] Error – ‘trust-cert’ sub task errored after 5.61 s
“Error trusting development certificate.”
[08:33:19] ‘trust-dev-cert’ errored after 5.62 s
[08:33:19]
[08:33:19] ==================[ Finished ]==================
Error – [trust-cert] Error: root “Trusted Root Certification Authorities”
Signature matches Public Key
CertUtil: -addstore command FAILED: 0x80070005 (WIN32: 5 ERROR_ACCESS_DENIED)
CertUtil: Access is denied.

Error – [trust-cert] Certificate trust failed with an unknown error.
Error – ‘trust-cert’ sub task errored after 5.61 s
“Error trusting development certificate.”

The only way I could manage to get around it was to manually create a cert using the OOB Windows tools.

Creating your .cer file

1. Start by locating makecert.exe. You can typically find it in and C:\Program Files (x86)\Windows Kits\8.1\bin\x64 on Windows Server 2012 R2.
2. Browse to that location with Command Prompt with Administrative privileges.
3. You can actually create a certificate to run against your machine name and you can also have it work against localhost. To create a certificate for your machine name, use the following command:

makecert -n “CN=%ComputerName%, CN=localhost” -ss MY -sr LocalMachine -b 08/09/2016 -e 09/09/2028 -a sha256 -sky exchange -r -pe myCert.cer

Return to where you tried to run trust-dev-cert and move to the next step.  We now have a dev cert so there is no use in creating one using gulp.

Thanks to Santi Murtagh for the instructions on setting up the cert.

Creating a Self-Signed SSL Certificate for Developing and Testing Against IIS