xgboost.core.XGBoostError: basic_string::resize

Dear Community,

when loading a trained XGBoost model I do get this error:
xgboost.core.XGBoostError: basic_string::resize

What does this error means and how to solve it? I did not find any valuable hint somewhere yet.

Version Mix-up between XGBoost this model was trained with and XGBoost this model is loaded with should be the same - I already checked it to my best knowledge.

Thank you very much!
Regards,
Johannes