After updating your DocuWare version it can happen that deleting documents (manually or via workflow) is not possible anymore.
You receive error messages like this:

"The DELETE statement conflicted with the REFERENCE constraint "FK4292ce99888f4b3f92f3ac944df0".

The conflict occurred in database "dwdata", table "dbo.BAUAKTE_SECT", column 'DWDOCID'.
The statement has been terminated."

Foreign Keys for _PAGE and _SECT tables of file cabinet or web basket location are not created correctly.

Foreign Keys have to be altered to correct options or have to be recreated. Following best practices for MYSQL, MSSQL and ORACLE.

Open MySQL Workbench and choose alter option for all your _PAGE and _SECT Tables in dwdata database. 
Correct settings should look like those shown in following screenshot.

For On Update select "RESTRICT", for On Delete select "CASCADE". Finally apply changes.

In Microsoft SQL Server Management Studio select foreign key of _PAGE and _SECT Tables in Object Explorer. In Context menu select "Script Key as" -->"Create To" --> "New Query Editor Windows">

Delete the existing foreign key.
Make sure the create statement for the foreign key contains "ON DELETE CASCADE" and run the create statement to recreate the foreign key with correct settings.
The statement should look similar to this:
Make sure that forein keys for _PAGE and _SECT tables contain "ON CASCADE DELETE" option. Recreate if this is not the case similar to what was described for MSSQL database.