I've switched my Account to the new Timeline yesterday evening. After I booted my PC today (ca. 17:40) i got a few notifications from FBuntu, but since then, not a single one (I've tried to check by telling friends to like my stuff). I assume it has to do with the switch from the old profile to the timeline. My OS is Ubuntu 11.10.
This is what Debug.log says:
2012-04-19 17:40:05 fbuntu.py:55 INFO: Update #1 starting
2012-04-19 17:40:05 graphNotificationChecker.py:32 INFO: Checking Facebook
2012-04-19 17:40:07 graphNotificationChecker.py:38 DEBUG: [{u'application': {u'namespace': u'awesomeprops', u'name': u'Likes', u'id': u'2409997254'}, u'from': {u'name': u'xxx', u'id': u'100000732952273'}, u'title': u'xxx likes your post in xxx.', u'updated_time': u'2012-04-19T13:43:08+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/events/305391332867371/312997908773380/', u'created_time': u'2012-04-19T13:43:08+0000', u'unread': 1, u'id': u'notif_100003616888715_1755925'}, {u'application': {u'namespace': u'wall', u'name': u'Wall', u'id': u'2719290516'}, u'from': {u'name': u'xxx', u'id': u'100002094443455'}, u'title': u'xxx wrote on your timeline', u'updated_time': u'2012-04-18T19:18:58+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/permalink.php?story_fbid=136190349844860&id=100003616888715', u'created_time': u'2012-04-18T19:18:58+0000', u'message': u'xxx': 1, u'id': u'notif_100003616888715_1729535'}, {u'application': {u'name': u'Events', u'id': u'141157392619610'}, u'from': {u'name': u'xxx', u'id': u'100001774290236'}, u'title'xxx posted in xxx "xxx"', u'updated_time': u'2012-04-18T19:55:57+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/events/305391332867371/313841478689023/', u'created_time': u'2012-04-17T19:52:19+0000', u'unread': 1, u'id': u'notif_100003616888715_1693081'}]
2012-04-19 17:40:07 graphNotificationChecker.py:65 DEBUG: Notification notif_100003616888715_1755925 not previously known about
2012-04-19 17:40:12 graphNotificationChecker.py:65 DEBUG: Notification notif_100003616888715_1729535 not previously known about
2012-04-19 17:40:13 graphNotificationChecker.py:65 DEBUG: Notification notif_100003616888715_1693081 not previously known about
2012-04-19 17:40:13 legacyInboxChecker.py:30 INFO: Checking Facebook
2012-04-19 17:40:15 legacyInboxChecker.py:67 DEBUG: []
2012-04-19 17:40:15 fbuntu.py:60 INFO: Ended update #1
2012-04-19 17:40:24 fbuntu.py:55 INFO: Update #2 starting
2012-04-19 17:40:24 graphNotificationChecker.py:32 INFO: Checking Facebook
2012-04-19 17:40:25 graphNotificationChecker.py:38 DEBUG: [{u'application': {u'namespace': u'awesomeprops', u'name': u'Likes', u'id': u'2409997254'}, u'from': {u'name': u'xxx', u'id': u'100000732952273'}, u'title': u'xxx likes your post in xxx.', u'updated_time': u'2012-04-19T13:43:08+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/events/305391332867371/312997908773380/', u'created_time': u'2012-04-19T13:43:08+0000', u'unread': 1, u'id': u'notif_100003616888715_1755925'}, {u'application': {u'namespace': u'wall', u'name': u'Wall', u'id': u'2719290516'}, u'from': {u'name': u'xxx', u'id': u'100002094443455'}, u'title': u'xxx posted on your timeline.', u'updated_time': u'2012-04-18T19:18:58+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/permalink.php?story_fbid=136190349844860&id=100003616888715', u'created_time': u'2012-04-18T19:18:58+0000', u'message': u'xxx', u'unread': 1, u'id': u'notif_100003616888715_1729535'}, {u'application': {u'name': u'Events', u'id': u'141157392619610'}, u'from': {u'name': u'xxx', u'id': u'100001774290236'}, u'title': u'xxx posted in xxx: "xxx"', u'updated_time': u'2012-04-18T19:55:57+0000', u'to': {u'name': u'Moritz Kr\xe4he', u'id': u'100003616888715'}, u'link': u'http://www.facebook.com/events/305391332867371/313841478689023/', u'created_time': u'2012-04-17T19:52:19+0000', u'unread': 1, u'id': u'notif_100003616888715_1693081'}]
2012-04-19 17:40:25 graphNotificationChecker.py:48 DEBUG: notif_100003616888715_1755925 is still unread
2012-04-19 17:40:25 graphNotificationChecker.py:48 DEBUG: notif_100003616888715_1729535 is still unread
2012-04-19 17:40:25 graphNotificationChecker.py:48 DEBUG: notif_100003616888715_1693081 is still unread
2012-04-19 17:40:25 graphNotificationChecker.py:60 DEBUG: Already know about notification notif_100003616888715_1755925 - in notificationArray at index 0
2012-04-19 17:40:25 graphNotificationChecker.py:60 DEBUG: Already know about notification notif_100003616888715_1729535 - in notificationArray at index 1
2012-04-19 17:40:25 graphNotificationChecker.py:60 DEBUG: Already know about notification notif_100003616888715_1693081 - in notificationArray at index 2
2012-04-19 17:40:25 legacyInboxChecker.py:30 INFO: Checking Facebook
2012-04-19 17:40:28 legacyInboxChecker.py:63 ERROR: Error 190 Error validating application. Invalid application ID.
Thanks for the bug report.
When Fbuntu encountered the error then it will have quit, and not tried to continue checking for messages and notifications. (You can tell it has quit because it doesn't show up in the messaging menu.)
Have you tried logging out and back in? (Or restarting the computer.) This will restart FBuntu and give it another chance. If you just get a second "Error 190" message in debug.log then let me know.