Causes
Inadequate terrarium conditions (temperature, humidity), lack of a suitable substrate or place to lay, poor nutrition, dehydration, malformations or eggs that are too large. Females can produce eggs even without a male present.
Diagnosis
Examination by an exotics vet + X-ray or ultrasound to see the eggs.
Treatment
EMERGENCY: correct the terrarium conditions, hydration, sometimes medication to promote laying. If this does not work, surgery to remove the eggs. The sooner, the better the prognosis.
Prevention
Keep the terrarium in optimal conditions for the species, always provide a suitable place to lay, good nutrition and hydration.

