When the real traitor in the dreyfus affair was discovered, what did french officials do?

First they refused to reopen the case.  Then they did a quick trial in which they found that person not guilty.  It wasn't till years later that Alfred Dreyfus was actually cleared of the false charges against him.

Captain Alfred Dreyfus (of Jewish ethnicity) had been accused of giving French military secrets to the Prussians.  The real traitor was Major Ferdinand Esterhazy (who had framed Dreyfus).  In 1896, when army intelligence chief Georges Picquart found evidence pointing to Esterhazy, he was rebuffed by army bosses and transferred to North Africa. When talk of Esterhazy's guilt persisted, the army court-martialed him but in a quick trial declared him not guilty.  The role of the media, led by an accusing article by Emile Zola, kept the Dreyfus Affair alive in public interest with a desire to undo the wrong that had been done to the innocent Dreyfus.  But it took till 1906 before Dreyfus was fully cleared of all guilt in the matter.