SQLite attempt to write a readonly database error

I have a console application that populates a SQLite database. When the application runs by itself, I don't get any errors. If I run multiple instances of the application, where each application is in its own folder and each populates its own database I'll occasionally get the following exception:

System.Data.SQLite.SQLiteException (0x80004005): Attempt to write a read-only database
attempt to write a readonly database
   at System.Data.SQLite.SQLite3.Reset(SQLiteStatement stmt)
   at System.Data.SQLite.SQLite3.Step(SQLiteStatement stmt)
   at System.Data.SQLite.SQLiteDataReader.NextResult()
   at System.Data.SQLite.SQLiteDataReader..ctor(SQLiteCommand cmd, CommandBehavior behave)
   at System.Data.SQLite.SQLiteCommand.ExecuteReader(CommandBehavior behavior)
   at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()

I know the DB isn't read-only because it has already written data to that database. Also, the app continues on and will continue populating data to that database. I haven't reproduced the error when only a single instance of the application is running.

I've tried using the pragma to have both the journal and temp_store in memory instead of to a file in case there could be some contention across applications there, but I still get the error. I do always get the error in the same method, which is the first time an insert would happen for the connection. To give a general idea of what the application does, it loops over cases, gathers info about those cases (not from SQLite), then writes results to the SQLite database.

I don't know what else to try.