FC Barcelona were unable to play their league match against Osasuna scheduled for last week because of the sudden death of a first-team doctor, Carles Minarro.

The Blaugranes had requested La Liga to postpone this game, and the Pamplona side also agreed to this, keeping in view the unprecedented situation.
As things stand, a date on which this postponed match will be played is yet to be decided, but according to Diario AS, this match is looking most likely to be played on May 21st, particularly as the two sides believe this is the best time to play this game.

One issue that can arise regarding this date is that it will come in between the final two matchdays of the league, and La Liga is not too keen to see Barcelona play their postponed match on this date as they will likely be competing for the league title.
Earlier, the organisers had put forward March 27th as a suitable date to schedule this game. However, both the involved clubs objected to it, as this comes right after the upcoming international break.

The Catalans would have been particularly affected by the selection of that date, as two of their players, Raphinha and Araujo, are likely to play for their respective international teams on 26th and 25th March respectively, and neither would be in a position to play again on 27th.
Thus, May 21st is emerging as the only viable date for now. However, La Liga can also decide to see how the Blaugranes’ UCL campaign goes, as more slots can open up if they get eliminated before the semi-finals, which are scheduled for April 29/30 or May 6/7.

Furthermore, if Barcelona are eliminated by Atletico Madrid in the upcoming second leg of the Copa del Rey semi-final, which currently stands at 4-4 on aggregate, April 26th, the day for the cup final, or the next day, can also be a suitable date to hold this postponed game.