dbup does not behave as expected

In MATLAB '25.1.0.2943329 (R2025a)', when in debug mode, calling dbup within a function behaves differently from calling dbup directly.

Save the following code as test_bug1:

function test_bug1(a,b)

c = a + b;

end

First, run

dbstop if error,

then call

test_bug1([1 2 3], [2 3]);

This will enter debug mode at the line c = a + b inside the test_bug1 function.

Executing dbup at this point behaves as expected and returns to the previous workspace.

However, if you define the following function:

function dbup_1()

dbup;

end

Executing dbup_1 at that moment results in an error, indicating that the current command is not a debugging command.

Similarly, if you create the following script and save it as dbup_2:

dbup;

Calling dbup_2 still results in the same error.

My question is: What causes the issue above?

If I want to include dbup, dbdown, and similar commands inside a function, how should I proceed?

[Adam Danz]

Accessing variables from a different workspace usually it not a good idea. What's the ultimate goal? Why can't it be realized by passing variables into the function?

[敬 杨]

You can refer to another question I asked for more details.

how to save the debugging state at matlab? - MATLAB Answers - MATLAB Central

Simply put, I would like to save the variables from every level of the function call stack when an error occurs in the program.

Answer 1

[Matt J]

There are special limitations on dbup, dbdown, and friends. You cannot call them from functions, because when a function is executing, you are not in debug mode anymore.

[Matt J]

Interestingly, though, I do find that you can invoke dbup from a Favorite Command (at least, you can in R2024b).

[Adam Danz]

This is documented in the dbup page, "dbup can only be called from the command line."

[Matt J]

Specifically, though, from the debugger command line:

>> dbup

Error using dbup

Debug commands only allowed when stopped in debug mode.

>> keyboard

K>> dbup

In base workspace.