Ansys General Error ~repack~ (REAL)

This is the #1 cause. When your model has millions of nodes or elements, the solver requires a contiguous block of RAM. If your machine runs out, the OS starts "paging" data to the hard drive. The solver, expecting nanosecond access speeds, times out and throws a general error.

In Fluent, a General Error often occurs during initialization or the first iteration.

Prevention is better than debugging a 36-hour simulation that failed at 99%.

Go to Tools > Advanced Settings and try assigning manual memory in MB according to what you have available on your PC rather than letting Ansys default to maximum.