Unable to create (first) Workbench application ("Failed to create application, please check if application name contains invalid string).

[#1]

Connection to local Livecycle server (ES4 trial) is working, service provider configured normally - Repository service 1.0 provider service is "RepositoryProviderService".

Error message is ambiguous and issue is definitely not with application name. This is a fresh installation so this may be a common pitfall with installation or configuration.

[#2]

Hi

I hope the service is in running state. Check the "DesigntimeService" too.

if it does not help, then also please check by configuring the service run as "Specify run as " as System on "repository provider service" and try again.

Also search for the services in stopped state. default services should all be in running state.