FF 60 ESR (latest) error

[moz666]

XML parsing error: error handling external entity reference URL: jar: file: /// *installation path*/browser/omni.ja! /Chrome/browser/content/browser/aboutPrivateBrowsing.xhtml Line number 9, column 3:
HtmlDTD%;
- ^

worked just fine yesterday.

[DanRaisch]

Close all applications and reboot the computer.
Delete any downloaded or partially downloaded installer files.
Clear the browser cache (of whatever browser you are using to download FF) and the Windows Temp directory.
Download a new copy of the full installer from www.mozilla.org/en-US/firefox/all
Delete the directory C:\Program Files\Mozilla Firefox
Run the installer.

[moz666]

that solved problem although with uninstallation new profile was made on (FF68 ESR) re-installation so had to hunt bookmarks, addons and abp blocklist again.

[Brummelchen]

you had an unsupported language file. in most cases an extra added language or a very outdated and no longer supported addon.

[moz666]

I had some addons which worked in older FF (and ESR like 5x) but didn't in FF60 and FF had disabled those (got replacements for most except download window) and no issues besides duplicate FF installations (older and newer) on Apps & Features (that's why I do uninstall and reinstall ~once a month). ABP-blocklist isn't what it was before FF bugging (too much work to put each blocked site in storage.js.migrated to their own row).

Profile survived from FF5x (non-ESR and ESR) to FF60.x but not to FF 68.