Steps to reproduce:
1. Create a database -> Start 6.2.x server -> Sign in as email@example.com.
2. Go to Site Admin -> Content -> Documents and Media -> Add a "Basic Document".
3. Go to Site Page -> Add a "Documents and Media" portlet.
4. Sign out the portal and shut down the server.
5. Add the following into portal-ext.properties file in master bundle.
6. Start the master server using the database as same as 6.2.x used.
7. Check the log file.
Upgrade successfully without any error.
Document cannot be upgraded from 6.2 to 7.0 because it throws com.liferay.portlet.documentlibrary.NoSuchFileException
Please refer to the attachment for the details of the log.