Quit using Mendeley people!
They started encrypting your database so you cannot easily move it over to other tools any more.
That link also helps you saving your data before it's too late.
(Elsevier are a bunch of crooks, blocking interoperability one-way and not the other. Almost as bad as Google blocking uBlock for your safety...)
@arjen I'm so glad I moved away from Mendeley a few years ago. I wrote a little PHP interface to manage a .bib file - https://github.com/christianp/bib-site - which powers http://read.somethingorotherwhatever.com/
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