This issue arises because SimBiology project files are not guaranteed to be forward-compatible, meaning they may not open in older releases. As a result, some project files created with MATLAB R2020a may encounter issues when opened in MATLAB R2019b. This is due to certain features and bug fixes present in MATLAB R2020a that are absent in MATLAB R2019b, leading to project loading problems.
Please review the following workarounds:
Workaround #1: Upgrade your MATLAB version
Upgrading to MATLAB R2020a/R2020b or latest releases can be a viable workaround.
Workaround #2: Use the backed-up SimBiology project
Starting with MATLAB R2020b, MATLAB will be backing up projects any time the project format changes (so MATLAB 2019b, 2020a projects will be backed up). For MATLAB R2020b, when a user opens a project saved in an older format, SimBiology attempts to save a copy of the original project in the same director (it will have the original release and '.backup' appended to its name). You should be able to open that backup file in MATLAB R2019b.
Workaround #3: Load the saved SimBiology models and re-build the project
Step 1: Please execute the following MATLAB command in your MATLAB R2020a.
>> sbioloadproject yourProjectName.sbproj
This will create variables that contain the models from your MATLAB R2020a SimBiology project. Save these models into MAT files, using the ‘save’ function.
Step 2: Open a blank project using the SimBiology APP in your MATLAB R2019b.
Step 3: Load the previously saved models into the project. Then modify your project according to your needs.
Note that this will lose any custom formatting in the diagrams in your original (MALTAB R2020a) project.
