I was getting an error when importing a csv file, by using the SSIS Flat File Source.
Error: 0xC020200E at Read Flat File : Cannot open the datafile "".
Error: 0xC004701A at Import File, SSIS.Pipeline: component "Read Flat File" (18) failed the pre-execute phase and returned error code 0xC020200E.
This was because the flat file source connection string was created by an expression. The expression used a parameter and this parameter was empty.
When the parameter was filled with the correct value, eg “C:\Data\Test.csv”, the error was solved.