1. The automation server cannot create objects.
Run: regsvr32 scrrun. dll.
2. The object reference is not set to the instance of the object.
1. The ViewState object is Unll.
2. DateSet is empty.
3. DataReader is empty due to SQL statements or Datebase.
4. When a string variable is declared, the variable is applied if no null value is assigned.
5. The new initialization object is not used.
6. The Session object is empty.
7. When a text value is assigned to the control, the value does not exist.
8. When Request. QueryString () is used, the obtained object does not exist, or the initial value is not assigned when the value is null.
9. When FindControl is used, the control does not exist but is not preprocessed.
Generally, in C #, the error "the instance where the object is not referenced" is that the control name does not correspond to that in codebehind. For Beginners, repeated definitions in encoding can also cause this problem.