In some cases, vote tallies do not add up. In others, precincts are shown allotting the wrong number of delegates to certain candidates. And in at least a few cases, the Iowa Democratic Party’s reported results do not match those reported by the precincts…

But not all of the errors are minor, and they raise questions about whether the public will ever get a completely precise account of the Iowa results. With Mr. Sanders closing to within 0.1 percentage points with 97 percent of 1,765 precincts reporting, the race could easily grow close enough for even the most minor errors to delay a final projection or raise doubts about a declared winner.

The errors suggest that many Iowa caucus leaders struggled to follow the rules of their party’s caucuses, or to adopt the additional reporting requirements introduced since 2016. They show that the Iowa Democratic Party, despite the long delays, failed to validate all of the results fully before releasing them to the public.