What was Stone convicted of?

BBC:

Stone was found guilty of lying to the House Intelligence Committee about his attempts to contact Wikileaks, the website that released damaging emails about Mr Trump’s 2016 Democratic election rival Hillary Clinton.

Guardian:

Stone, 67, was convicted in November 2019 of obstructing a congressional investigation into whether the Trump campaign colluded with Russia to win the 2016 election.

Los Angeles Times:

Prosecutors never established that Stone had coordinated with WikiLeaks, but they said Stone lied to the House Intelligence Committee to cover up his efforts and to protect Trump.

They said he also encouraged Randy Credico, a comedian and talk show host, to withhold information from lawmakers.

Frankfurter Allgemeine:

In der Russland-Affäre hatte FBI-Sonder­ermittler Robert Mueller die Vorwürfe zu illegalen Beziehungen zwischen dem Trump-Wahlkampfteam – für das auch Stone arbeitete – und Vertretern Russlands untersucht. In der im Frühjahr vergangenen Jahres abgeschlossenen Untersuchung fand Mueller keine Belege dafür, dass es vor der Wahl 2016 Geheimabsprachen zwischen dem Trump-Wahlkampfteam und Vertretern Russlands gegeben habe.