The main reason why an OST file is not accessible on other systems is that it is tied to the specific Outlook profile and Exchange server it was created on, while a PST file can be opened on any system. In such cases, a converter is required to open the OST file in Outlook.

There are several common reasons why you may need to convert an OST file to PST:

Disconnection from the Exchange Server
Configuring an IMAP account in Outlook (2013 or later)
Synchronization issues
Corrupted OST file
...and many other scenarios.
To effectively migrate data from OST to PST format, a reliable solution is necessary. One such solution is Goldytools OST to PST Converter. This user-friendly, single-wizard application allows for seamless conversion of OST files to PST, ensuring your data is easily accessible in any Outlook instance.