I had a package that I copied and updated to a new connection.  The package runs successfully.  But when I open it it shows the following error.

Error loading Master DatawarehouseETL.dtsx:  The connection “{42E5886D-F897-4366-9794-02AF8E32198D}” is not found.

Everything runs.  So what is the problem?

The problem is I have steps that are disabled.  SSIS still checks the connections even though the step is disabled.  The package runs since the step does not run.  I fixed the connection and the error goes away.