Refer to the following release notes for the major releases of DsPdfViewer.   

• Release Notes for Version 4.2.0
• Release Notes for Version 4.1.0
• Release Notes for Version 4.0.0
• Release Notes for Version 3.2.0
• Release Notes for Version 3.1.2
• Release Notes for Version 3.0.10
• Release Notes for Version 2.2.15
• Release Notes for Version 2.2.11
• Release Notes for Version 2.1.14
• Release Notes for Version 2.0.10
• Release Notes for Version 1.2.88
• Release Notes for Version 1.1.56
• Release Notes for Version 1.0.42

For details about latest hot fixes, see the nuget page.