What led to the Noida workers’ protest?

The story so far:

The Noida workers’ protest, which turned into widespread violence on April 13, has become a major crisis for the Uttar Pradesh government. The unrest, sparked mainly by demands for higher wages and improved working conditions, paralyzed parts of the city’s industrial areas and triggered a major security response. On April 14, domestic workers working in high-rise buildings such as Cleo County also began protesting for a wage increase. The administration adopted a dual approach of pressure and concessions. In direct response to the unrest, the Uttar Pradesh government issued a statement. 20-21% increase in minimum wages, effective retroactively from April 1. As Uttar Pradesh heads towards elections, the situation has given the Opposition an issue to corner the government on.