According to the MTA, riders will not be able to buy or load OMNY Cards this weekend because of a system upgrade. (Advance/SILive | Erik Bascome)The Metropolitan Transportation Authority is warning OMNY users to make sure their cards are loaded before this weekend. The system upgrades will last from 10 p.m. on Friday, Oct. 3, to 7 p.m. on Sunday, Oct. 5. OMNY cards can still be used during that time, but travelers will not be able to buy new cards or add value to existing cards. The MTA stated that OMNY card users should load their account before the upgrade starts or tap their phone, debit card, or credit card to pay.