This is usually due to misconfigured system proxy settings or security software on your system interfering with Zotero Standalone's ability to connect to https://sync.zotero.org/. Make sure that your system proxy settings are fully disabled if not in use, and try temporarily disabling your security software. You can also check the certificate info, though that would usually produce a different error.
Thanks for your response. I've sorted it out and it was something to do with the time and date on my laptop being wrong. I corrected the time and date and Zotero synced perfectly after that.
Unfortunately, my time and date only stays right for about half an hour so I will have to keep correcting it if I want Zotero to sync properly throughout the day.... I realise there is nothing you can do about this though!
Upgrade Storage
Unfortunately, my time and date only stays right for about half an hour so I will have to keep correcting it if I want Zotero to sync properly throughout the day.... I realise there is nothing you can do about this though!