I have a project that serves as an internal set of tools. Because of this I have need for multiple contexts. I have one context setup fine, then I started trying to add my second context. I learned from another SO question that you need to rename the Configuration file(s) after enabling, and then reference the new configuration file name when doing Add-Migration and Update-Database commands. I did this and ended up with the "Unable to generate an explicit migration..." which references 201605181623556_ServiceRequest which as you can see below was applied.
PM> Enable-Migrations -ContextTypeName InsideAdminContext
At this point I renamed the configuration file InsideAdminConfiguration
PM> Enable-Migrations -ContextTypeName PartFinderContext
Renamed the configuration file PartFinderconfiguration
PM> Add-Migration "ServiceRequest" -ConfigurationTypeName InsideAdminConfiguration
PM> update-database -ConfigurationTypeName InsideAdminConfiguration
Applying explicit migrations: [201605181623556_ServiceRequest].
Applying explicit migration: 201605181623556_ServiceRequest.
Running Seed method.
PM> Add-Migration "InitialMigrationForPartFinder" -ConfigurationTypeName PartFinderConfiguration
Unable to generate an explicit migration because the following explicit migrations are pending: [201605181623556_ServiceRequest]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
So far I have deleted all the migration folders, deleted the table and _MigrationHistory table and started over with the commands above, but the problem persists.
-----UPDATE-----
I reversed the order of above and created the PartFinder tables first and ended up with the same error when trying to Add-Migration on ServiceRequest.