Many of founder Mark Zuckerberg's old posts have vanished from Facebook, and won't be restored.
Some were a record of key moments in the company's history.
Their absence was first noted by Business Insider, which was told by the social network that the posts were "deleted due to technical errors".
Facebook will not try to retrieve them because the process would be too complicated and not guaranteed to work, the company said in a statement. While Facebook backs up data, it has changed its archive system along the way.
The company could not say how many of Zuckerberg's posts had been deleted.
Business Insider says important details about core events in Facebook's history are now "obscured".
It says it's hard to make a full accounting of the vanished posts, but we know many existed because they were quoted, in part, in media at the time.
One of Zuckerberg's now-absent posts was written in April 2012 as Facebook acquired Instagram for US$1 billion.
"It was an important document in the history of Facebook, particularly given Zuckerberg promised that 'we're committed to building and growing Instagram independently' – a commitment he has since walked back," Business Insider says.
Another deleted post involved the death of Facebook's "beloved" head chef Josef Desimone in a motorcycle crash in July 2013.
Facebook would go on to throw a party in Desimone's memory at its headquarters the following month - a boozy event attended by hundreds where, according to media reports, gang-related fights broke out.
Business Insider also notes that some posts are missing en masse. It says Zuckerberg was very active on Facebook during in the late 2000s, but all posts from 2007 and 2008 are gone.