Can't add new Feeds - TypeError: Cannot read property 'code' of undefined

Tiny Tiny RSS Support
1

Hi,

I just noticed that I can no longer add new feeds to my tt-rss installation. The error message I get is as follows (domain is changed):

> TypeError: Cannot read property 'code' of undefined
>     at https://tt-rss.my-domain.com/js/CommonDialogs.js?1567310403:122:28
>     at onComplete (https://tt-rss.my-domain.com/js/common.js?1549190323:26:32)
>     at klass.respondToReadyState (https://tt-rss.my-domain.com/lib/prototype.js?1549190323:1827:62)
>     at klass.onStateChange (https://tt-rss.my-domain.com/lib/prototype.js?1549190323:1756:12)

I run updates on a fixed schedule using git pull but I don’t know exactly when this started.

tt-rss 19.8 (81bf112)
Ubuntu 18.04 LTS
PHP 7.2.19
AWS t2 instance

Maybe you can take a look.

Thanks in advance and best regards