Why do I receive the error "Simulink cannot load the initial operating point"?

I received the error during simulation:

Simulink cannot load the initial operating point because the model, 'myModel', was changed after the operating point was saved. Run the simulation again and resave the operating point.

I find it hard to deduce the root cause during debugging from this error message. How to resolve this error?

Answer 1

[MathWorks Support Team]

Error explanation 

The error message means that a structural change was made to the model between when the Operating Point was captured and when it was applied. Structural changes can include:

• Adding or removing of blocks or signals
• Changes to signal datatype or dimension

Example

For example, consider the model below where "myVar" is "true", this makes the output signal type "boolean". 

Now consider if we override that variable as shown below

sim_input = sim_input.setVariable('myVar', 1);

The '1' here is interpreted as double. Since this variable is used in other Constant blocks in the model, and each of these blocks is set to "Inherit: Inherit from 'Constant value'". This changes the datatype of some signals in the model, which then changes the model checksum from when the operating point was captured and thus throwing the error.

You may change the line below and the simulation should run without error:

sim_input = sim_input.setVariable('myVar', true);

Use checksum details to find difference

If you are struggling to find the exact change in your model that is causing the issue, you can use the checksum details (similar to the doc page below), to compare the checksum of the model from the Operating Point capture to operating point apply. 

https://www.mathworks.com/help/simulink/slref/determining-why-simulink-accelerator-is-regenerating-code.html

Attached is a simplified example that hopefully demonstrates the issue and also includes an example tool called getChecksumDiff(), which is an example of how you can compare the checksum of the two versions of the model to hopefully better diagnose these types of issues in the future.

The development team is considering improving the error message to point directly to the offending change that is causing the loading of the Operating Point to fail.