We are using Meraki to install an App (AdHoc) onto some iPads. It has been setup and working for about 4 years. Today I tried and uninstall and reinstall the App onto an iPad and it's giving the error "Could not validate manifest" when it tries to install the App. The .ipa file has not been modified since December and was successfully installed onto 8 iPads at the time with no problem. I have tried a second iPad and it also gives the same error.
The push certificate and iOS Distribution certificate are all valid.
We are having the same issue within our organization. I have exhausted all of our resources trying to resolve this issue. Our applications were installing fine up until yesterday. It seems to be a much larger issue at play if this many people are experiencing the same problem.