If an internal DocuWare database version 1 is still running on a locally installed DocuWare system, it must be upgraded before you can upgrade to DocuWare version 7.4. With this older version 1, it is also no longer possible to log into Web Client in DocuWare version 7.4.
Before upgrading, be sure that your customers are already using the current version 2 / MySQL 5.6 as their internal database or perform an appropriate update.
Detailed instructions and technical notes on database updates can be found in this Knowledge Base. Links can be found in PartnerInfo 305. If you have any questions, please contact DocuWare Support.