Tried my usual link this morning - and BI launched as it should!

Until the fix you may run BI from Cmd. Tested and working. Start Command prompt, Run as Administrator and type: "C:\Program Files\Blue Iris 5\BlueIrisAdmin.exe" You can also make a batch file using a text editor. Write the above line of code(with quotation marks), name the file something ...

Same for me - no updates, working fine yesterday - now blocked.