Not sure if this is posted in the right forum or if to use for anyone. But now it is here if it can be useful for anyone.
We recently upgraded to a new version of UiPath (2018.3) and encountered a couple of issues that have now been solved.
E.g. we experienced a problem with executing the “Open Browser” activity. The error message was saying “Cannot communicate with Internet Explorer browser”. Also we experienced that it was not possible to launch the Ui Explorer.
The solution was found in Microsoft AppLocker that was blocking the activities to run properly. A change to the GPO “whitelisting” the UiPath working directory solved this.
The “Send Exchange Mail” was also experiencing some problems. The error message was saying “The AutoDiscover service couldn’t be located”. Apparently it seems that the password for all assets of the type credential was set to nothing. Re-entering the password seemed to do the trick.