Webhook is disabled once in a few days

Bk13 If Dropbox is repeatedly unable to successfully deliver webhook notifications to your webhook URI server, it will stop attempting to do so. At that point, your webhook URI will be disabled, you will be notified of this by email, and no further webhook notifications will be sent until the webhook URI is re-enabled. You should be able see any available error information, though only while the webhook URI is failing, on the app's page on the App Console.

As Здравко said, be careful how you manage your webhook URI handler; the Dropbox servers expect the response to be returned quickly. You can find more information in the Webhooks documentation.

Additionally, if there are any network issues preventing the request from reaching your server, that would also be considered a failure, and you wouldn't necessarily see exceptions from your code, so you may want to check with your network admin for any potential network issues.