What does this mean and how to solve it?

Hi, I'm new here and I don't have much experience using spss.
To carry out my master's thesis, I am using spss to run a logistic regression model.
The problem is that every time I run the model, the following warning appears:
"Unable to calculate parameter covariance matrix. The remaining statistics will be omitted."
What am I doing wrong and how do I fix this?