Some important reasons for the missing back rent:

Many tenants began withholding rent because they had been dealing for years with unsafe conditions, while others fell behind because they could not afford their monthly payments, according to the tenant union. They may now get a blank slate.

Kuo said tenants dealt with a range of problems in their buildings including caved-in ceilings, heat outages and, at times, darkened hallways after Con Edison cut the common area electricity due to the landlord’s unpaid bills.