I got an error in deploying the Portal to SAIL plugin to 7.4

This indicates an issue in the primary data source. How are you deploying the plugin? What database are you using? Take a look at the dt_model table. There should be a few hundred rows in that table.

At first, we are using SQL server as primary data source. Secondly, the Appian 7.4 is an new installation, that is not migrated from Appian 7.3. At last, there are only the following 6 data type in dt_model creating by Appian:
NAME           NAMESPACE_URI
PortalReportDT1           http://types.appiancorp.com/ps
PortalReportCellDT2           http://types.appiancorp.com/ps
VariantDT3           www.appian.com/.../2009
PortalReportColumnDT4           http://types.appiancorp.com/ps
VariantDT5           www.appian.com/.../2009
PortalReportColumnDataDT6 http://types.appiancorp.com/ps

If there are only 6 entries in dt_model then that would likely cause the issue you are seeing. Can you create a new primary datasource and try deploying with that? Make sure to update your application server and custom.properties as appropriate.

Looking at the DT_MODEL table it seems that somebody deployed this plug-in before but then some records where deleted from this table. As you can see this plug-in uses at least 11 CDTs but your DT_MODEL only has 4.

Another option is that when the plug-in was deploying somebody interrupted the deployment by shutting down the app server which means that the smart service got registered in Process Design but did not create all the CDTs in the DT_MODEL table, so now when you deploy it again Design knows it had been here before so it tries to find the CDTs in the DT_MODEL to compare them with the ones that are about to be installed to determine whether there was a change or not.

We'll follow-up offline with you to solve this.

Eduardo, Thanks for your reply.