Entity Framework with MySql and Migrations failing because “max key length is 767 bytes”

Answer paraphrased from Adding custom MigrationHistory context…

EF6 uses a MigrationHistory table to keep track of model changes and to ensure the consistency between the database schema and conceptual schema. This table does not work for MySQL by default because the primary key is too large. To remedy this situation, you will need to shrink the key size for that table.

Essentially, EF6 allows you to modify the key size for the MigrationId/ContextKey index columns using Fluent API like so:

modelBuilder.Entity<HistoryRow>().Property(h => h.MigrationId).HasMaxLength(100).IsRequired();
modelBuilder.Entity<HistoryRow>().Property(h => h.ContextKey).HasMaxLength(200).IsRequired();

Complete Instructions Here…