[XXpcOQpAICwAAAGO6PgAAABN] 2019-09-12 14:54:49: Fatal exception of type "Flow\Exception\InvalidDataException"
Discussion page is not available for this particular user. Not sure what are the conditions for this to happen. The user is blocked but the User_talk page works fine for other blocked users
This was reported as related to T232696: Block prevents replying to Flow threads but it doesn't look as such