Clear evidence of instability in the electricity grid was present even before the large-scale blackout on 28 April 2025, according to Executive Digest.

The population saw the blackout as unexpected, but company calls with Spanish operator Red Eléctrica show otherwise. Audio recordings reveal operators detected and reported grid fluctuations, but no timely action was taken, leading to the collapse in Portugal, Spain, and parts of France.

Spanish newspaper El Mundo first reported this, confirming that failure alerts were present after reviewing recordings given to the Senate committee investigating the incident.

On 26 April 2025, two days before the blackout, a company manager told the operator, “I’m calling to find out what’s happening, because we’re experiencing a lot of fluctuations.” The same issue was reported on 16 April.

Despite repeated warnings and requests for checks—including warnings about possible automatic disconnections—audio recordings show that operators did not take preventive action.

The audio recordings may prove that the blackout was caused by the operator's negligence and failure to respond appropriately to repeated warnings, as the operator stated, "We don't have time to regulate it."