Short answer
There is no historical evidence for it. A story spread online says Christians tricked the Muslims of Granada on 1 April, but Granada surrendered by treaty on 2 January 1492, and no source from the time links April Fools' Day to it. The real suffering of Spain's Muslims came later, through forced conversion and expulsion.
This is a history question, not a fiqh one. Historians agree that Granada fell in January 1492 and that the origins of April Fools' Day are unclear and unrelated. Lying to fool people is blameworthy in Islam whatever its history.
The four schools agree on this.
Explanation
A popular message claims that the Christian kings of Spain told the Muslims they could leave safely by ship, then burned the ships on 1 April, and that Europeans celebrated the trick every year since. The story is moving, but it does not match the record.
The last Muslim kingdom in Spain, Granada, surrendered to Ferdinand and Isabella by treaty. The handover took place on 2 January 1492, and the last sultan, Muhammad XII (Boabdil), left for North Africa. No source from the period, Muslim or Christian, links that event to 1 April or to pranks. The origins of April Fools' Day are themselves unclear; early references come from France and the Low Countries in the sixteenth century and have nothing to do with Spain.
The real tragedy is well documented. The treaty promised Muslims freedom of religion, but within a decade the crown forced them to convert. Those who converted, called Moriscos, were watched and persecuted, and between 1609 and 1614 they were expelled from Spain. Muslims can honour that history without repeating a story that is not true.
Whatever its origin, April Fools' pranks often involve lies. The Prophet ﷺ warned against the one who lies to make people laugh. Muslims should avoid lies and frightening tricks, and should also check stories before sharing them. On the wider era, see Islamic Golden Age.
The evidence
Quran, Surah Al-Hujuraat 49:6
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِن جَآءَكُمْ فَاسِقٌۢ بِنَبَإٍۢ فَتَبَيَّنُوٓا۟ أَن تُصِيبُوا۟ قَوْمًۢا بِجَهَٰلَةٍۢ فَتُصْبِحُوا۟ عَلَىٰ مَا فَعَلْتُمْ نَٰدِمِينَ ﴿٦﴾
O you who have believed, if there comes to you a disobedient one with information, investigate, lest you harm a people out of ignorance and become, over what you have done, regretful.
Check news before passing it on.
Sunan Abi Dawud 4990
Graded hasan... ويل للذي يحدث فيكذب ليضحك به القوم ...
"Woe to the one who speaks and lies to make people laugh."
Lying for a joke is blameworthy; graded hasan.
Where the ruling is recorded
- Nafh al-Tib (al-Maqqari), Section on the fall of Granada and the end of Muslim rule in al-Andalus. The classical Muslim account of the fall of Granada.
- Riyad al-Salihin (al-Nawawi), Book of forbidden matters, chapter on the prohibition of lying. Gathers the hadith against lying, including in jest.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.