Given less than two months to build an app for reporting caucus results to the Iowa Democratic Party, Shadow produced technology that proved difficult to download and use and ended up delivering incorrect tallies. Iowa’s Democrats blamed a “coding issue” in the app, and the party said it would resort to a time-consuming manual tally based on information called in by precinct chairs or pictures sent on their smartphones — the same ones on which they could not make the app work.

With the wait on results dragging into Tuesday evening, many in the party began dissecting what turned the Democrats’ first contest of the 2020 election into a chaotic display, starting with Shadow, and its main backer, Acronym, a progressive nonprofit that is focused on helping Democrats regain their digital edge.

Shadow, in a tweet, said, “We sincerely regret the delay in the reporting of the results of last night’s Iowa caucuses and the uncertainty it has caused.” But the company offered no explanation for what went wrong, though Democratic officials said that data had been incorrectly transmitted from the app to a central database, and that many users had been unable to follow the complicated process for installing the app on their phones.

The fallout spread quickly on Tuesday. Nevada, which like Iowa holds caucuses instead of a primary election, said it was abandoning plans to use Shadow’s app. The Biden campaign, which had hired Shadow to help it reach voters, announced that it had cut ties with the company last year.