The thing that moves a router from pending to routed is a call to target-ready. That call isn’t happening, which is leading to the failed state. The default macro calls target ready after starting the new report. I’ve never had that fail, but if starting the report threw an exception then it would never route.

see report-will-enter in reports.cljc in RAD

that’s the implementation of the routing will-enter handler for things generated by defsc-report

Hmm, I think the issue here is that report-will-enter calls start-report!, which in turn tries to trigger :event/resume as long as there is any ::uism/active-state. Since :will-enter can be called multiple times at the start of route resolution, the first call can put the report in :state/loading and a subsequent call will see that it's got an active-state and will try to trigger :event/resume, for which there is no handler. I believe this is what leads to this error: > UNEXPECTED EVENT: Did not find a way to handle event :event/resume in the current active state: :state/loading See ... Does this seem like a bug to you, @U0CKQ19AQ? https://github.com/fulcrologic/fulcro-rad/blob/2e668d5ce271299c5efc4f2748a3b021534d5a6a/src/main/com/fulcrologic/rad/report.cljc#L529-L532

> The thing that moves a router from pending to routed is a call to target-ready. I think something different is happening here. I don't route directly to a report because I start+render the report myself in a defsc. Here's a diagram of my layout. It looks like the TabRouter is doing fine, but the MainRouter doesn't get updated as it should. Is there anything obvious that could cause that which I'm missing? And it doesn't happen every time. Maybe 1 of 5 or so... which makes it harder to track down.

sounds like a problem in your logic for the target of the MainRouter…RepoProfile isn’t calling target-ready correctly, or perhaps your Tab1-Report wrapper isn’t doing the start of the state machine for the report correctly. Impossible to tell without looking over all of the code.

I think I've finally gotten to the bottom of it. The RepoProfile uses Tab1 as the first route. In RP's :will-enter, I was calling start-report! on Tab1-Report. However, I was routing to Tab1 (leaf node), which also called start-report! on the same Tab1-Report. I guess this was creating some conflicting ops where the timing of the load played a factor, leading to the intermittent failures. The solution was to only call start-report in RP's :will-enter and to do a dr/route-immediate in the tab's :will-enter. Thank you for the suggestions, @U0CKQ19AQ. Every time some issue like this kicks my ass I always end up learning a bunch. The fact that Fulcro only has so much surface area makes me optimistic that eventually I'll have it covered. I suppose there is no way to detect conflicting simultaneous loads like this beyond debugging the resulting errors?

I do a combination of things: I look at logs, and I actually read the errors. If nothing pops out, then I consider the primitives: how do they work. That usually narrows it down to just a few possibilities.