Here is an article in English:

https://nltimes.nl/2025/10/29/ns-hit-microsoft-cloud-outage-...

It should be noted that the article isn't complete: while the travel planner and ticket machines were the first to fail, trains were cancelled soon after; it took a few hours before everything restarted.

Based on what the conductors said, I would speculate that the train drivers digital schedule was not operative, so they didn't know where to go next.

Thanks! Perhaps one of the sites that track train delays can give a statistic?

This list doesn't have anything that looks relevant: https://www.rijdendetreinen.nl/en/disruptions/archive?date_b...

The day does not appear as an outlier in the monthly statistics: https://www.rijdendetreinen.nl/en/statistics/2025/10

I don't find a detailed statistic on the overall delays, but the per-station statistics for Amsterdam Centraal say 5% of trains were cancelled and 17% were delayed by 5 minutes or more (mostly by 10 minutes): https://www.rijdendetreinen.nl/en/train-archive/2025-10-29/a...