Hi, I recently came across this error when trying to login to the Company Apps Portal on a Windows 8 Phone. The exact error message displayed is:
“Sorry, but we’re having trouble signing you in Please try again in a few minutes. If this doesn’t work, you might want to contact your admin and report the following error: 8004789A.”
This error message is very similar to the one experience by my colleague Richard Knight in his blog post “Error when federated user tries to sign in to the Office 365 portal with error: 8004789A”
And as detailed in Richard’s post, the issue occurred because we were publishing the ADFS URL through TMG and the resolution is to disable the “Apply link translation to this rule” on the rule where the ADFS URL is published in TMG.