.pst file asking for password but never assigned one to it

The issue seems to occur because of the original PST file was residing on a network drive.

The problem is - if you attempt to open Outlook when the default PST file is unavailable (e.g. because the network drive takes too long to establish itself), Outlook will create a new default PST file having the same name.

In this case, this new PST file somehow acquired a password. I suspect when it happened, my wife was prompted whether she wanted to set a password for the new file, and entered something not realising what she was doing.

In any case, going into Control Panel and editing the Outlook mail settings from behind the scenes to set the original PST file as the default cured the problem.

To get to these settings, go to Cortana and enter 'run'

Then enter 'control' to run Control Panel.

In 'Search Control Panel' enter 'mail'

And launch 'Mail (Microsoft Outlook 2016) (32-bit)'

Select 'Data Files' and change the settings to point Outlook to the correct PST file.

You may fine a new, very small Outlook PST file on the local drive having the same name as the original PST file.

Once fixed, run Outlook and it should launch as normal.

Please mark as "Accept the answer" if the above steps helps you. Your suggestion will help others also !

Hi @SY_MSO ,
To verify your issue, how did you import PST file?
Refer the article below which provides information to import Outlook items:
import email contacts and calendar from an outlook pst file
What’s the detailed version of Outlook? (File > Office Account >About Outlook)

it is prompting for a password to the .pst file which they never assigned/created.

When the password pops up, will there be an error message if you click to continue directly?

In addition, can you open this PST file via File > Open/Export > Open Outlook Data File?
If so, it is recommended to break up the large .pst file and manually move messages from your large .pst file to another .pst file.
Here is an article for your reference: Create an Outlook Data File (.pst)
(1)Make sure that your large .pst file and another .pst file are both opened in Outlook.
(2)Right-click the folder that you want to move to other smaller .pst files.

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