Asalamualikum just to confirm, based on the view that filling the front row is mandatory, if I arrive late to Salah and see 1 spot available in the front row, but filling it would cause hardship by blocking an exit, may I pray in the row behind with others? Would I be sinful, and is my Salah valid?

Ustadh AbdulAziz al-Haqqan
Your salah is valid on every view.