htmlsnapshot supports reporting error code for SnapUrl function. This can help you decide the problem of failing to snap certain pages.

 It works like this:

snap.SnapUrl(…..) 

 iErrorCode=snap.GetErrorCode()

The error code is an interger value which has following values:

0: The normal state.

1: The snapshot is successfully taken.

-1: Fail to take the snapshot of the page, check if your html image is too big to be fit into memory,

-2: Fail to save to file, check if you can write to the output image path

-3: Fail to open the URL. check network please

-4: Time is out before taking a snapshot, use a larger time out value or call SetForceSnap before snapping.