Sorry. This is the first time I'm reporting this problem but not the first time it's happened. My computer Zotero library was working fine and then when I typed a citation title in the search bar my entire library disappeared from view and in its place read 'Zotero encountered an error. report error in actions'. I closed down Firefox and tried to reopen my Zotero library and now I'm just getting an alert pop-up saying 'there was an error starting Zotero'. My library won't open at all. I work on a MacBook Air, Mac OS 10.8.5.
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https://www.zotero.org/support/reporting_problems#provide_steps_to_reproduce