UPDATE: JULY 14 2024: This issue has been fixed. Updates made at the NCBI-end have fixed the issue with NCBI and UniProt sequence downloads. SnapGene 7.2.1 and earlier versions can now download NCBI/UniProt files directly from within SnapGene. See Import a Sequence from NCBI and Import a Protein Sequence.
NCBI have recently made changes to their site which has broken our importer for all NCBI and Uniprot files (via menu File → Import → NCBI sequences... or File → Import → Uniprot sequences...). This issue affects all versions of SnapGene and SnapGene Viewer.
Users who try to download files will see an error message.
Our developers are investigating. Once we understand the cause of the issue we will release an update of SnapGene 7.2 with a fix.
Until this is fixed with a SnapGene update, the best option is to download the full GenBank or Uniprot record as a GenBank file from the database website and import the downloaded file into SnapGene.
If you want a region of the sequence, open the GenBank file in SnapGene, select the region of interest and use Extract a Region in a Sequence to a New File.