In Sweden, the Cancer Foundation and several newspapers belonging to Bonnier Local News are affected.
On its website, Heroku writes that they are working to solve the problem that arose on Friday morning.
Bonnier Local News includes about 40 local newspapers and sites such as Bandypuls and Hockeypuls.
Newspapers such as Gefle Dagblad, Sundsvalls Tidning, Jönköpings-Posten and Östersunds-Posten are affected by the problems.
"We currently have technical problems that make it difficult to log in to JP.se. We are aware of the technical outage and our IT department is troubleshooting what it is about. For the time being, you will be redirected to our news feed on Facebook ", writes Jönköpings-Posten in a post on Facebook.