This is caused by a failing check on the server for the context you entered. I can see the error message "Fehler beim..." in the top-right corner.

Could you see if you can locate the error, for example in the javascript console or using the developer tools? Are you using firebug, it has a nice console and network tab you can use to see what happens on submitting the new-todo form.

any update?

Sorry, I was busy. I'm not the server admin and don't know the technical side of the tracks installation. Here's a log the admin gave me (what was logged when I created a test todo in the "Recherche" context that already exists).
If this is not helpful, please specify detailed steps on how to get useful information on this.

Started POST "/todos" for 89.14.213.3 at Tue Jun 04 19:10:58 +0200 2013
Processing by TodosController#create as JS
Parameters: {"default_project_name"=>"", "authenticity_token"=>"\"96aaCTs4VyHIiLWn8/qiNOvJvfccGaod2YyIHqVQ3P4=\"", "19"=>"a", "18"=>"t", "17"=>"_", "16"=>"&", "15"=>"
g", "14"=>"a", "13"=>"t", "12"=>"=", "11"=>"w", "10"=>"e", "predecessor_input"=>"", "default_context_name"=>"Recherche", "tag_list"=>"starred", "33"=>"d", "32"=>"e", "3
1"=>"r", "30"=>"r", "predecessor_list"=>"", "todo"=>{"description"=>"error", "due"=>"", "show_from"=>"", "notes"=>"new contexn"}, "new_todo_starred"=>"false", "initial_
tag_list"=>"starred", "project_name"=>"", "9"=>"i", "8"=>"v", "7"=>"_", "6"=>"e", "5"=>"c", "4"=>"r", "3"=>"u", "2"=>"o", "1"=>"s", "0"=>"_", "context_name"=>"Recherche
", "utf8"=>"?", "29"=>"a", "28"=>"t", "27"=>"s", "26"=>"=", "25"=>"e", "24"=>"m", "23"=>"a", "22"=>"n", "21"=>"_", "20"=>"g", "_tag_name"=>"starred", "_source_view"=>"t
ag"}
ESC[1mESC[36mUser Load (0.1ms)ESC[0m ESC[1mSELECT `users`.* FROM `users` WHERE `users`.`id` = 1 LIMIT 1ESC[0m
ESC[1mESC[35mPreference Load (0.1ms)ESC[0m SELECT `preferences`.* FROM `preferences` WHERE `preferences`.`user_id` = 1 LIMIT 1
ESC[1mESC[36mContext Load (0.3ms)ESC[0m ESC[1mSELECT `contexts`.* FROM `contexts` WHERE `contexts`.`user_id` = 1 AND `contexts`.`name` = 'Recherche' ORDER BY positio
n ASC LIMIT 1ESC[0m
ESC[1mESC[35mCACHE (0.0ms)ESC[0m SELECT `contexts`.* FROM `contexts` WHERE `contexts`.`user_id` = 1 AND `contexts`.`name` = 'Recherche' ORDER BY position ASC LIMIT 1
ESC[1mESC[36m (0.0ms)ESC[0m ESC[1mBEGINESC[0m
ESC[1mESC[35mContext Load (0.2ms)ESC[0m SELECT `contexts`.* FROM `contexts` WHERE `contexts`.`id` = 15 LIMIT 1
ESC[1mESC[36mSQL (0.8ms)ESC[0m ESC[1mINSERT INTO `todos` (`completed_at`, `context_id`, `created_at`, `description`, `due`, `notes`, `project_id`, `recurring_todo_id`, `rendered_notes`, `show_from`, `state`, `updated_at`, `user_id`) VALUES (NULL, 15, '2013-06-04 17:10:58', 'error', NULL, 'new contexn', NULL, NULL, '<p>new contexn</p>', NULL, 'active', '2013-06-04 17:10:58', 1)ESC[0m
ESC[1mESC[35mTodo Load (0.2ms)ESC[0m SELECT `todos`.* FROM `todos` INNER JOIN `dependencies` ON `todos`.`id` = `dependencies`.`predecessor_id` WHERE `dependencies`.`successor_id` = 535
ESC[1mESC[36mSQL (0.3ms)ESC[0m ESC[1mUPDATE `contexts` SET `updated_at` = '2013-06-04 17:10:58' WHERE `contexts`.`id` = 15ESC[0m
ESC[1mESC[35m (146.3ms)ESC[0m COMMIT
ESC[1mESC[36m (0.1ms)ESC[0m ESC[1mBEGINESC[0m
ESC[1mESC[35mSQL (0.2ms)ESC[0m UPDATE `contexts` SET `updated_at` = '2013-06-04 17:10:59' WHERE `contexts`.`id` = 15
ESC[1mESC[36m (21.1ms)ESC[0m ESC[1mCOMMITESC[0m
ESC[1mESC[35m (0.1ms)ESC[0m BEGIN
ESC[1mESC[36mTag Load (0.1ms)ESC[0m ESC[1mSELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'starred' LIMIT 1ESC[0m
ESC[1mESC[35mSQL (0.2ms)ESC[0m INSERT INTO `taggings` (`tag_id`, `taggable_id`, `taggable_type`) VALUES (1, 535, 'Todo')
ESC[1mESC[36mTodo Load (0.3ms)ESC[0m ESC[1mSELECT `todos`.* FROM `todos` WHERE `todos`.`id` = 535 LIMIT 1ESC[0m
ESC[1mESC[35mSQL (0.1ms)ESC[0m UPDATE `todos` SET `updated_at` = '2013-06-04 17:10:59' WHERE `todos`.`id` = 535
ESC[1mESC[36mContext Load (0.2ms)ESC[0m ESC[1mSELECT `contexts`.* FROM `contexts` WHERE `contexts`.`id` = 15 LIMIT 1ESC[0m
ESC[1mESC[35mSQL (0.1ms)ESC[0m UPDATE `contexts` SET `updated_at` = '2013-06-04 17:10:59' WHERE `contexts`.`id` = 15
ESC[1mESC[36m (44.6ms)ESC[0m ESC[1mCOMMITESC[0m
ESC[1mESC[35mTag Load (0.3ms)ESC[0m SELECT `tags`.* FROM `tags` INNER JOIN `taggings` ON `tags`.`id` = `taggings`.`tag_id` WHERE `taggings`.`taggable_id` = 535 AND `taggings`.`taggable_type` = 'Todo'
ESC[1mESC[36m (0.2ms)ESC[0m ESC[1mSELECT COUNT(*) FROM `todos` INNER JOIN `dependencies` ON `todos`.`id` = `dependencies`.`predecessor_id` WHERE `dependencies`.`successor_id` = 535 AND (NOT (todos.state = 'completed'))ESC[0m
ESC[1mESC[35m (0.0ms)ESC[0m BEGIN
ESC[1mESC[36mSQL (0.1ms)ESC[0m ESC[1mUPDATE `contexts` SET `updated_at` = '2013-06-04 17:10:59' WHERE `contexts`.`id` = 15ESC[0m
ESC[1mESC[35m (157.4ms)ESC[0m COMMIT
ESC[1mESC[36mTodo Load (0.3ms)ESC[0m ESC[1mSELECT `todos`.* FROM `todos` WHERE `todos`.`id` = 535 LIMIT 1ESC[0m
ESC[1mESC[35mTag Load (0.1ms)ESC[0m SELECT `tags`.* FROM `tags` WHERE `tags`.`name` = 'starred' LIMIT 1
ESC[1mESC[36m (0.7ms)ESC[0m ESC[1mSELECT COUNT(*) FROM `todos` INNER JOIN taggings ON todos.id = taggings.taggable_id INNER JOIN contexts c_hidden ON c_hidden.id = todos.context_id WHERE `todos`.`user_id` = 1 AND `todos`.`state` = 'active' AND (taggings.tag_id = 1 ) AND (NOT(todos.state = 'project_hidden' OR (c_hidden.hide = 1 AND (todos.state = 'active' OR todos.state = 'deferred' OR todos.state = 'pending'))))ESC[0m
ESC[1mESC[35mContext Load (0.1ms)ESC[0m SELECT `contexts`.* FROM `contexts` WHERE `contexts`.`id` = 15 LIMIT 1
ESC[1mESC[36mTag Load (0.1ms)ESC[0m ESC[1mSELECT `tags`.* FROM `tags` INNER JOIN `taggings` ON `tags`.`id` = `taggings`.`tag_id` WHERE `taggings`.`taggable_id` = 535 AND `taggings`.`taggable_type` = 'Todo'ESC[0m
ESC[1mESC[35mTodo Load (0.4ms)ESC[0m SELECT `todos`.* FROM `todos` INNER JOIN `dependencies` ON `todos`.`id` = `dependencies`.`predecessor_id` WHERE `dependencies`.`successor_id` = 535 AND (NOT (todos.state = 'completed'))
Read fragment views/todos/535-20130604171059/20130604/tag/false/f6b1f1676905500ed5685760722d24b6 (9.9ms)
ESC[1mESC[36m (0.3ms)ESC[0m ESC[1mSELECT COUNT(*) FROM `todos` INNER JOIN `dependencies` ON `todos`.`id` = `dependencies`.`successor_id` WHERE `dependencies`.`predecessor_id` = 535 AND (todos.state = 'pending')ESC[0m
Write fragment views/todos/535-20130604171059/20130604/tag/false/f6b1f1676905500ed5685760722d24b6 (0.9ms)
Rendered todos/_todo.html.erb (25.2ms)
Rendered todos/create.js.erb (33.5ms)
Completed 200 OK in 531ms (Views: 54.5ms | ActiveRecord: 375.5ms)

AFAICS, the create on your server is working fine. I guess that the problem is in the AJAX call from the browser to the server to check on the existence of the context you entered.

Can you see the traffic from the browser to the server, for example with firebug? It could tell why the call to check the context fails. It may be your SSL config

Yes, there's something wrong with the certificate, I have to add my tracks page to Firefox' exceptions. (Not sure if it was self signed or completely wrong since it's one VPS that can be accessed by several domain names.

Will provide more details later.

could also be a mismatch between your tracks url and the url in the certificate. if the full url does not match the url in the certificate, browsers will refuse.

still, if tracks is working with the exception, so should the AJAX calls. I'm using a self-signed certificate which also needs an exception in the browsers, but AJAX is working.

Yes, I'm somewhat sure that the URL I use to access tracks is not the one in the certificate (Will check that later with my admin).

However, aside from the faulty "Create new context?" dialog, everything works. So if everything else can handle the certificate problem, why can't the check for context existence? (If that's really the problem).

When I'll have time I'll talk to my admin and try what will happen when I access tracks through the URL that's in the certificate.

it could be that the AJAX call is not done over SSL which is a configuration issue. But you should look at the traffic from your browser like I wrote above.

I have the same issue here, however I do not use SSL: I am on a free Heroku account. Is there any quick fix? It's really annoying.

I cannot reproduce is myself. Perhaps if you can give me a testaccount to your tracks so I can see myself?

closing for now. Please reopen if necessary. I cannot reproduce.