Why do I get an iostream stream error 'iolib:badbit' in Simulink Test Manager when running my test cases in R2019b?

In some cases my test file/suite runs fail with the error:

An error occurred ('iolib:badbit') when calling 'sim':

Error writing to output stream.

iostream stream error

Answer 1

[MathWorks Support Team]

Since the "iolib:badbit" error is related to printing to iostreams, please check the following:

1. What is the duration for which the test is run?

• If you have a long simulation time: Does the error still occur when reducing the duration?

2. Is the harness model producing text output to the MATLAB command window when run outside of Simulink Test Manager?

• Might there be forgotten semicolons in m scripts?
• Or is any other logging information printed during the simulation run?
• Might there be a modeling issue that causes many messages to be generated under certain conditions?

Anything causing the output stream to be too long will lead to this error.

Please check your model regarding the hints given above (specifically under item 2).