nexturl work as expected and return a valid page - it should never result in a 500 error.
modified" must always be an integer,
afterChangeNumbermust also be an integer.
afterChangeNumberof the next url always increase with each new page - if not the query has likely been badly implemented.
deleted" items in the feed. If these are missing, it is likely the feed has not been implemented correctly.
nextURL should be an absolute not relative URL.
nextURL present on the last page? The
nextURL on the last page should match the URL of the current page.