Using 10.0.7 on Open SuSE LEAP 42.3.
I turned off encryption an decrypted the whole site (took several hours), seems to have worked, no error messages.
Then I disabled the encryption app.
The pdf-reader app is active.
When I click on a pdf document (which is no longer encrypted), I get 503 and log says "no encryption module active" or the like. Then I reactivated the encryption app. Now I get a different error: Private key not found.
When I de-activate the pdf-reader app, I can download the pdf file without problems.