nav-blocked

{ ok: false, reason: 'blocked', code: 'nav-blocked', by: '<plugin or step>', url: '…/errors/nav-blocked' }

Returned, not thrown, by next(), back() and go(). Nothing is written.

Four things refuse with blocked, and by says which one it was:

Refused by	by names
a plugin’s beforeNavigate	the plugin, or the name it returned in { block }
the step’s guards.exit	the step being left
the navigation policy on go()	the target
the target’s guards.enter	the target

The policy and an enter guard both name the target, so the result alone does not tell them apart. go(to, { force: true }) does: force skips the policy, and a move it still refuses was refused by a guard. A flow without policy gets visited, which refuses a jump to a step that has not been visited yet.

If the refusal is the rule working, show the user why they cannot go on. If it is not, the condition is what is wrong: correct the guard, or the plugin, or set the flow’s policy. Guards run on every move, force included. API behaviour has all three switches side by side.