When downloading manga from Tsumino, you may get the error “Tsumino cookie is expired”. This means that Tsumino has started blocking image downloads until you solve their captcha.
At the current time, HDoujin does not have a built-in way of dealing with the captcha. To get around this, you will need to solve the captcha in your browser and then copy the session cookie into HDoujin using the Cookie Editor.
In your browser, open the reader for any manga (e.g., the one you want to download), and solve the captcha that appears. Then copy the value of the “ASP.NET_SessionId” cookie from your browser into HDoujin, and click “Edit Existing Cookie” to replace the existing value (if the cookie does not already exist, just fill out the fields as below and click “Add New Cookie” instead).
Reset the item that is showing the error, and it should start working again. Try to limit the number of items you download from Tsumino at once, as too many simultaneous requests will trigger the captcha faster.