Can't preview or download files from browser


PDF.js v1.9.426 (build: 2558a58d)
Message: Unexpected server response (503) while retrieving PDF "".

when previewing nextcloud flyer



Service Unavailable

Technical details

Remote Address:
Request ID: XchAUJOhFyCivUUPZ7qf@wAAAEo
Nextcloud – a safe home for all your data

when trying to download it.

Using on Ubuntu 18.04, nextcloud (re)installed via snap package.
I think there are a lot of things missing in the documentation.

Check the Nextcloud log file for any messages (exceptions etc.) related to this problem