When I have tried syncing OmniFocus 2.0.4 (under OS X, 10.9.5) very recently, I have encountered a warning and so cancelled the connection. The warning is as follows: “The server certificate for “sync.omnigroup.com” is not signed by any root server. This site may not be trustworthy. Would you like to connect anyway?” I’ve seen this message each time I’ve attempted to sync today, using different WiFi networks. By contrast, OmniFocus for iPhone (2.4.4) has been able to sync without difficulties.
I’ve seen another thread about certificate signatures, but the issue seemed to be about involvement of an unexpected party. Here, “Thawte Premium Server CA” is listed, however. Whether or not a coincidence, I had recently installed a few updates (including Security Update 2015-004) and it was after the update process that I began having problems, but I would not have expected this to affect the signature of a certificate. The details I see are shown below:
Has anyone else encountered this issue recently? What is the safest way to proceed?