fix skype for business certifacate error
1 Delete the certificate and try to sign in to Skype for Business Online. 2  If you can't sign in to Skype for Business Online, go to step 2. 3  If you're running Windows 7, remove the userâs stored credentials in Windows Credential Manager.4  To do this, follow these steps: 5  Open Control Panel, and then click Credential Manager.dditionally, when you try to sign in to Lync after a network outage or a Skype for Business Online service outage, you receive the following error message: There was a problem acquiring a personal certificate required to sign in. If the problem continues, please contact your support team. Cannot sign into Lync.