In Grapher 16, the Grapher file format was changed so that it can open files saved in newer versions of Grapher. For example, Grapher 16 can open a GRF saved in Grapher 17. 

Grapher 15 and older cannot open Grapher files that were created in newer versions (referred to as forward compatibility). For example, Grapher 14 cannot open Grapher 15 files. If you'd like the ability to open GRF, GPJ, and GRT files in any version of Grapher 16 and newer, get the latest version of Grapher. 

This error typically occurs during one of two scenarios. Each are listed below, along with a solution: 

Scenario 1: If you have recently re-installed, or transferred computers, it's possible you accidentally downloaded the wrong version. Open Grapher and click Help | Check for Update or File | Online | Check for Update, or, follow these instructions to download the newest installer you are eligible to use from our My Account portal: Download my software online.  

Scenario 2: You received this file from another individual. Tell them what version you are running (click Help | About or File | About), and ask them to send the file in the version you are running. They can do this by clicking File | Save as and changing the Save as type to the appropriate version file type. You also might consider getting current with Grapher.

Updated March 2020