I am getting CastInvalid Error Message . I verified all the datatypes . It looks good. I dont know where this error is pointing.

You don't need the CAST. You can simply have the following:

a!forEach(
    items: local!productInfo,
    expression: 'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information'(
      /* map your attributes from each instance of fv!item to your CDT attributes */
    )
  )

You don't need the CAST. You can simply have the following:

a!forEach(
    items: local!productInfo,
    expression: 'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information'(
      /* map your attributes from each instance of fv!item to your CDT attributes */
    )
  )

Thank you :). But in my other expression i am doing casting which is working i am not sure why i am getting error. However this solution works fine. Let me integrate this with process model and see if it actually post the data to db 

  a!forEach(
  items: local!productinfo,
  expression: 
  'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information'(
    
      serialNumber: fn!index(fv!item, "EOXInputValue", null),
      createdBy: loggedInUser(),
      createdOn: now(),
      modifiedBy: loggedInUser(),
      modifiedOn: now(),
      eOlproductId: fn!index(fv!item, "EOLProductID", null),
      productIdDescription: fn!index(fv!item, "ProductIDDescription", null),
      productBulletinNumber: fn!index(fv!item, "ProductBulletinNumber", null),
      linkToProductBulletinUrl: fn!index(fv!item, "LinkToProductBulletinURL", null),
      eOxExternalAnnouncementDate: fn!index(fv!item, "EOXExternalAnnouncementDate", null),
      endOfSaleDate: fn!index(fv!item, "EndOfSaleDate", null),
      endOfSwMaintenanceReleases: fn!index(fv!item, "EndOfSWMaintenanceReleases", null),
      endOfSecurityVulSupportDate: fn!index(fv!item, "EndOfSecurityVulSupportDate", ""),
      endOfRoutineFailureAnalysisDate: fn!index(fv!item, "EndOfRoutineFailureAnalysisDate", null),
      endOfServiceContractRenewal: fn!index(fv!item, "EndOfServiceContractRenewal", null),
      lastDateOfSupport: fn!index(fv!item, "LastDateOfSupport", null),
      endOfSvcAttachDate: fn!index(fv!item, "EndOfSvcAttachDate", null),
      updatedTimeStamp: fn!index(fv!item, "UpdatedTimeStamp", null),
      pIdActiveFlag: fn!index(fv!item, "PIDActiveFlag", null),
      migrationProductInfoUrl: fn!index(fv!item, "MigrationProductInfoURL", null),
      migrationInformation: fn!index(fv!item, "MigrationInformation", null),
      migrationProductId: fn!index(fv!item, "MigrationProductId", null),
      migrationProductName: fn!index(fv!item, "MigrationProductName", null),
      migrationStrategy: fn!index(fv!item, "MigrationStrategy", null),
      migrationOption: fn!index(fv!item, "MigrationOption", null),
    
  ),

Note: if you want to use CAST (which is valid) you need to lose the () suffix from your type! statement i.e.

a!forEach(
    items: local!productInfo,
    expression: cast(
      'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information',
      {
        /* map your attributes from fv!item to your CDT attributes here*/
      }
    )
  )

This is because the instruction type!'<myType>'() is a function to create an instance of your CDT, whereas type!'<myType' is a reference to the type number, and CAST requires the type number of a type not an instance of the type.

see my explanation below

Good Catch. I missed it.

Yup, just need to be aware that if you let Appian auto-complete your type! statement it will add the () function suffix. It's caught me out in the past...

Yeah. Learned from mistakes. I never forget.. I was breaking my head all looks good why it was failing. then after remove this "()" it fixed the issue. Anyway i learned two things.. We can cast using cast function else using type function to cast directly. 

Thanks again :) for your prompt response. Appian community is fast in responding the queries. Exploring Appian..