My app crashes when deployed on the free tier meteor.com

I have been running my app on the free meteor.com tier for over a year without any problem, but lately it crashes, see logs below. I haven’t changed anything to my app lately and it runs fine on my local machine. I have deleted it from meteor.com and re-deployed, but it just keeps crashing…
Here is the logfile:

meteor logs youtopx.meteor.com
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] WARNING /meteor/dev_bundles/0.4.18/lib/node_modules/fibers/future.js:278
throw(ex);
^
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] WARNING MongoError: auth failed
at Object.Future.wait (/meteor/dev_bundles/0.4.18/lib/node_modules/fibers/future.js:398:15)
at packages/meteor/helpers.js:119:1
at new FS.StorageAdapter (packages/cfs:storage-adapter/storageAdapter.server.js:256:1)
at new FS.Store.GridFS (packages/cfs:gridfs/gridfs.server.js:46:1)
at app/lib/defs/mediafile-defs.js:6:15
at app/lib/defs/mediafile-defs.js:26:3
at /meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/boot.js:222:10
at Array.forEach (native)
at Function._.each._.forEach (/meteor/dev_bundles/0.4.18/lib/node_modules/underscore/underscore.js:79:11)
at /meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/boot.js:117:5
- - - - -
at Object.toError (/meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/utils.js:110:11)
at /meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/auth/mongodb_cr.js:39:33
at /meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/db.js:1806:9
at Server.Base._callHandler
(/meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/connection/base.js:442:41)
at /meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/connection/server.js:485:18
at [object Object].MongoReply.parseBody
(/meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/responses/mongo_reply.js:68:5)
at [object Object].<anonymous>
(/meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/connection/server.js:443:20)
at [object Object].emit (events.js:95:17)
at [object Object].<anonymous>
(/meteor/containers/9a1e6764-8c7e-d0be-1f52-595f28975b22/bundle/programs/server/npm/cfs_gridfs/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:191:13)
at [object Object].emit (events.js:98:17)
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] ERROR Application crashed with code: 8
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] NOTICE Starting application on port 29642
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] INFO STATUS running -> starting
[Sun Feb 21 2016 11:49:19 GMT+0000 (UTC)] INFO STATUS starting -> running
[Sun Feb 21 2016 11:49:22 GMT+0000 (UTC)] INFO Meteor._wrapAsync has been renamed to Meteor.wrapAsync
[Sun Feb 21 2016 11:49:27 GMT+0000 (UTC)] WARNING /meteor/dev_bundles/0.4.18/lib/node_modules/fibers/future.js:278