Today I found Duplicati couldn’t work again - this issue just happened last month, today I just found this issue caused by CCleaner, I used it yesterday, and it cleared all credentials in windows credential storage.
I reconfigue all backup in WebUI (using previous passphrase and backup destination, so it needn’t start backup from scratch). Maybe this is ths easist way.
Thank you for your reply. I just found I login via systray, so I haven’t set passphrase (not used for encrypt backup file) manually, hence in this situation, automatically export backup configuration (to remote, like WebDAV storage) is a better solution.