Mercedes-Benz confirmed on Sunday that a bottleneck in certain components led to the cancellation of a shift at its key Sindelfingen plant on Friday. The company did not identify the parts or suppliers involved.

The disruption comes amid a debate over labor costs in Germany. Auto industry expert Ferdinand Dudenhöffer backed Mercedes-Benz’s position on extending working hours without extra pay. He called the standard 35-hour workweek outdated and a threat to Germany’s competitiveness.

The debate follows recent warnings from Mercedes-Benz production chief Michael Schiebe that the company could close two German plants if it does not achieve significant cost reductions.