Error while create 1 unmanage solution and exporting as manage solution from Dev crm 2016 online and import to UAT crm 2016 online as manage solution

Error while create 1 unmanage solution and exporting as manage solution  from Dev crm 2016 online and import to UAT crm 2016 online as manage solution

Errror :

Export error :

The following components are missing from your solution. Import will fail if these components don't exist already in the target Microsoft Dynamics CRM organization. To add the missing components to your solution, cancel import, open the solution, and click the Add Required Components button.

Import error:

The import of the solution failed. The following components are missing in your system and are not included in the solution. Import the managed solutions that contain these components (Active) and then try importing this solution again.

please guide me