When you try to access notes in a section in OneNote Online that has been protected with a password, you may get an error message telling you that the section cannot be opened. It means that whoever owns the shared notebook you’re working in (or another author) has locked the section.
If you need to view or work in the protected notes, you might have to check with that person to get the password for that section.
To open a password protected section, do the following:
In OneNote Online, click the name of the protected section that you’re trying to open.
When OneNote tells you that the section is password-protected, press the Enter key on your keyboard (or click the message with your mouse).
When prompted, enter the password to unlock the section.
Unlocked protected sections will stay unlocked while you are working in them. However, if you step away for a while, or if you close OneNote Online, the section will be automatically locked again, and you’ll need to re-enter the password the next time you try to access the notes within it.
If you want change the current password for a protected section or if you want to protect a section that hasn’t been locked before, you’ll need to open the notebook in one of the OneNote desktop or mobile apps listed below: