I’ve encountered the same problem (on newgrounds), seed 62742335367, here is the error message from the Web Console:
Uncaught Failed to generate TheVaultOfYendor:1 after 40 attemps. level-generate.js:60:4
generateLevel https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/level/level-generate.js:60
changeLevel https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/level/level.js:134
zoneTo https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/level/level.js:341
func https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/character/player.js:1549
execute https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:32086
dispatch https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:31884
updateFX https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:29861
update https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:29806
postUpdate https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:33130
updateLogic https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:38321
update https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:38251
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67700
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682
(Async: FrameRequestCallback)
updateRAF https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67702
_onLoop https://uploads.ungrounded.net/alternate/5246000/5246699_alternate_242866_r5.zip/phaser.js:67682