There may be problems when data is changed, an error might have occurred.

For most women, young or old, the error occurred before they were born.

Only one or a few pictures would come off the drive each time before an error occurred.

Anna's first error occurred when she was 16 months old.

This error occurs when the hard drive is (nearly) full.

In the process, they will need to identify and correct those cases where errors have occurred.

At the same time errors could have occurred as the studies were done on animals rather than humans.

Some errors occur when an individual is distracted by something else.

The error occurred six weeks after the hospital introduced a new system for testing blood.

You should do this by giving a full explanation in writing as to how the error occurred.