The national blackout investigation deepened as Red Eléctrica delivered its "black box" data to government investigators, who requested additional information from operators. In the morning, news emerged that Moncloa was exploring whether a cyberattack on facilities outside Red Eléctrica caused the outage, especially relevant given reports the Catalan government received 6.9 billion cyberattacks last year.

Two towns revealed they maintained power during the blackout through special isolation systems, offering a technical counterpoint to the cascade failure. Labor unions used May Day demonstrations to advocate for reducing working hours, specifically pressuring Junts not to block the initiative.

Minister Díaz demanded accountability for the "archimillionaire" costs while opposing BBVA's takeover bid of Sabadell bank (which Competition Authority approved yesterday). By evening, the investigation commission announced it would visit Red Eléctrica on Saturday to gather more information.