Unfortunately due to er1 being such an old file type, our latest version 2019 R1 cannot open them. You would have to upgrade the model using multiple versions of the erwin DM software. Here is the upgrade path:
Steps:
1. Open the model in version 3.5.x and save
2. Open the 3.5.x model in erwin 4.1.4 sp3 and save
3. Open the 4.1.4 model in 7.3.x and save
4. 9.8+ will open models from 7.3.x (both are .erwin format)
This is clearly a tedious process and we don't expect customers to have all of these versions downloaded. Alternatively, if the customers are allowed to send us the model we can upgrade the model for them and send it back to them.
