Proteus Save For Older Version ((link)) Online

Proteus is a popular electronic design automation (EDA) software used for designing, testing, and simulating electronic circuits. The software is widely used by engineers, students, and hobbyists for creating and testing electronic circuits. However, with each new version of Proteus, the file format for saving projects changes, making it difficult for users to open and work on projects created in older versions.

In their knowledge base (article KB 1045), Labcenter states: proteus save for older version

Proteus Design Suite, developed by Labcenter Electronics, is one of the most powerful and widely used software packages for electronic circuit design, simulation, and PCB layout. Its two main components— (for schematic capture and simulation) and ARES (for PCB layout)—have evolved significantly over the years. Proteus is a popular electronic design automation (EDA)