LogFAQs > #986195597

https://www.cbc.ca/news/canada/ottawa/pride-parade-cancelled-after-being-halted-by-pro-palestinian-protesters-1.5554689

Ottawa's annual Pride parade was cancelled on Sunday after it was halted by a local pro-Palestinian advocacy group that blocked the road and demanded to negotiate with organizers.
The group Queers for Palestine Ottawa (Q4P) halted the parade "with the permission" of the grand marshal, the organization said in a press release issued Sunday afternoon just as the parade was stopped.

Seems like it was a ways along before being halted, then there was some confusion for a couple hours before cancelling entirely.