Add-in Error of complements in Word Online with my Personal Account

Since it works in desktop Word and with the university account, a Mendeley installation failure is unlikely. First test whether the personal account can reach the Office add-in catalog. In Word for the web, create a blank document in OneDrive, open Home > Add-ins > More Add-ins, refresh My Add-ins, and try a free add-in.

If the catalog fails, sign out of Microsoft accounts, close Office tabs, clear site data for office.com and live.com, then sign in only with the personal account. Temporarily allow third-party cookies and pop-ups for Office, because web add-ins load hosted content and authentication can fail when cross-site storage is blocked. Retry in a normal window.

If another add-in works, remove and re-add Mendeley. If none work only with the personal account, contact Microsoft 365 consumer support with the error, UTC time, browser, and subscription details. That indicates an account/catalog service problem rather than the document.