It is solved by opening the relay browser once. I believe it is caused by idling out and scheduling an adventure with mafia through the gCLI or adventuring panel without using the relay browser. I have experienced it several times, including about 5 minutes ago like this - gCLI log to follow:
> call bounty *
Checking for updates (running Bounty Hunter Helper ver. 1.1.1)...
Running Bounty Hunter Helper version: 1.1.1 (current)
8 drops of filthy ichor from big creepy spider
10 rusty tap handles from claw-foot bathtub
9 purple butts from jungle baboon
Accepting the hunt for 8 drops of filthy ichor from big creepy spider...
8 drops of filthy ichor from big creepy spider
10 rusty tap handles from claw-foot bathtub
9 purple butts from jungle baboon
Now hunting: 8 drops of filthy ichor from big creepy spider
Adventuring for 8 drops of filthy ichor from big creepy spider...
Condition added: filthy lucre
Casting Leash of Linguini 1 times...
You acquire an effect: Leash of Linguini (duration: 10 Adventures)
Leash of Linguini was successfully cast.
Searching for "Knob Goblin eyedrops"...
Search complete.
Purchasing Knob Goblin eyedrops (1 @ 200)...
You acquire an item: Knob Goblin eyedrops
You spent 200 Meat
Purchases complete.
Using 1 Knob Goblin eyedrops...
You acquire an effect: Peeled Eyeballs (duration: 10 Adventures)
Finished using 1 Knob Goblin eyedrops.
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
KoLmafia declares world peace.
[2125] The Sleazy Back Alley
> call bounty *
8 drops of filthy ichor from big creepy spider
10 rusty tap handles from claw-foot bathtub
9 purple butts from jungle baboon
Now hunting: 8 drops of filthy ichor from big creepy spider
Adventuring for 8 drops of filthy ichor from big creepy spider...
Conditions list cleared.
Condition added: filthy lucre
Request 1 of 453 (Town: The Sleazy Back Alley) in progress...
[2125] The Sleazy Back Alley
Encounter: hung-over half-orc hobo
Strategy: C:\Program Files (x86)\KoLmafia\ccs\WHAMbeta.ccs [default]
The first 2125 was me opening up the relay browser, which didn't actually start adventure 2125, but made mafia aware that would be the next adventure. I re-ran the same call bounty * and then it actually ran adventure 2125.
What really should happen for debugging this would be a debug log. I don't have that yet. My suspicion though is that this is caused by the "hit main.php on initial login as well as when mafia idles out" addition not working properly when mafia idles out.
