Hi all,

I periodically get errors in Zotero where it won't sync to the group libraries I use with my research team.

I am not running a proxy; Zotero Standalone doesn't have a proxy settings tab; Windows Firewall is configured to let Zotero through; and the only anti-virus etc. I am running is Windows Defender. Also, sync works like 95% of the time; it's only periodically that it doesn't work.

Here's the error message:

[JavaScript Error: "Error connecting to server. Check your Internet connection." {file: "chrome://zotero/content/xpcom/sync.js" line: 2595}]
[JavaScript Error: "Error connecting to server. Check your Internet connection." {file: "chrome://zotero/content/xpcom/sync.js" line: 652}]
[JavaScript Error: "Unable to access cssRules property of http://static.squarespace.com/universal/styles-compressed/simple-liking-09fa291ec2800c97714f0d157fd0a6ca-min.css in wpdDOMSaver.processCSSRecursively()" {file: "chrome://zotero/content/webpagedump/domsaver.js" line: 655}]
[JavaScript Error: "Unable to access cssRules property of https://css.washingtonpost.com/wp-stat/ad/loaders/latest/css/wp.css in wpdDOMSaver.processCSSRecursively()" {file: "chrome://zotero/content/webpagedump/domsaver.js" line: 655}]
1491328303795 addons.update-checker WARN Update manifest for zoteroOpenOfficeIntegration@zotero.org did not contain an updates property
1491328303825 addons.update-checker WARN Update manifest for zoteroWinWordIntegration@zotero.org did not contain an updates property
[JavaScript Error: "1491328303830 addons.xpi ERROR Failed to clean updated system add-ons directories.: Win error 2 during operation DirectoryIterator.prototype.next on file C:\Users\alice\AppData\Roaming\Zotero\Zotero\Profiles\9retzqlr.default\features (The system cannot find the file specified.
) ((unknown module)) No traceback available" {file: "resource://gre/modules/Log.jsm" line: 751}]
[JavaScript Error: "Error connecting to server. Check your Internet connection." {file: "chrome://zotero/content/xpcom/sync.js" line: 2595}]
[JavaScript Error: "Error: Error connecting to server. Check your Internet connection." {file: "chrome://zotero/content/xpcom/sync.js" line: 652}]

version => 4.0.29.17, platform => Win32, oscpu => Windows NT 10.0; WOW64, locale => en-US, appName => Zotero, appVersion => 4.0.29.17, extensions => Zotero LibreOffice Integration (3.5.12.SA.4.0.29.17, extension), Zotero Word for Windows Integration (3.5.6.SA.4.0.29.17, extension), Adobe Acrobat (15.23.20053.15062, plugin), Google Update (1.3.32.7, plugin), Microsoft Office 2016 (16.0.7830.1013, plugin)

Any ideas would be MUCH appreciated! I've tried all sorts of things.