: You can use the Nitro Migration Assistant to move your library items, stamps, and user preferences from PDFpen Pro 13.1 to the newer Nitro version. Key Updates from Version 13.1

If you are updating to 13.1 from an earlier version, this build included several significant enhancements:

For users still on version 13.1, several common stability and performance "fixes" have been identified:

: If the application is slow or freezing (especially on M1 Macs), users are advised to perform a clean install or launch the app while holding the Shift key to prevent it from reopening previous windows.

The software previously known as has been rebranded and updated to Nitro PDF Pro following Nitro's acquisition of Smile Software. If you are experiencing issues with version 13.1, the primary "fix" recommended by the developer is migrating to the latest Nitro-branded version. Resolving Issues in PDFpen Pro 13.1

Pdfpen Pro 13.1 Fix May 2026

: You can use the Nitro Migration Assistant to move your library items, stamps, and user preferences from PDFpen Pro 13.1 to the newer Nitro version. Key Updates from Version 13.1

If you are updating to 13.1 from an earlier version, this build included several significant enhancements: PDFpen Pro 13.1 fix

For users still on version 13.1, several common stability and performance "fixes" have been identified: : You can use the Nitro Migration Assistant

: If the application is slow or freezing (especially on M1 Macs), users are advised to perform a clean install or launch the app while holding the Shift key to prevent it from reopening previous windows. If you are experiencing issues with version 13

The software previously known as has been rebranded and updated to Nitro PDF Pro following Nitro's acquisition of Smile Software. If you are experiencing issues with version 13.1, the primary "fix" recommended by the developer is migrating to the latest Nitro-branded version. Resolving Issues in PDFpen Pro 13.1