This error will occur if you are using running SnapGene on a computer account that previously had SnapGene installed while using a Sassafras-based shared license. Follow the instructions below to fix this error.
macOS
1. Quit SnapGene.
2. Type command-space (Spotlight Search) and search for the phrase "terminal". Hit return to run the Terminal application.
3. Copy and paste the following command (one line) into the Terminal window and hit return.
rm ~/Library/Application\ Support/SnapGene/.klf
4. Run SnapGene and activate with your license, see Download, Install, and Activate SnapGene.
Windows
1. Quit SnapGene.
2. Click the Windows button and search for the phrase Command Prompt and run the "Command Prompt" program.
3. Copy and paste the following command (one line) into the Terminal window and hit return.
del /AH %AppData%\SnapGene\.klf
4. Run SnapGene and activate with your license, see Download, Install, and Activate SnapGene.