--- title: "Decision Points when an OST File is Disconnected and Outlook won’t Open" date: 2026-04-03 author: "Sofia Ramirez" featured_image: "https://sqmagazine.co.uk/wp-content/uploads/2026/03/ost-file-disconnected.jpg" categories: - name: "Technology" url: "/technology.md" tags: - name: "SP" url: "/tag/sp.md" --- # Decision Points when an OST File is Disconnected and Outlook won’t Open Microsoft Outlook uses an Offline Storage Table or OST file to keep a local, synchronized copy of mailbox items on the server. This file needs to be constantly connected to the mail server to ensure uninterrupted email flow and synchronization. At times, you face a situation where the OST file gets disconnected from the server. Such an issue can disrupt your day-to-day workflow and email communication. In this article, we will look into the reasons for a disconnected OST file and the decisions you can take when this happens. ## Why does the OST file get disconnected from the Mail Server? **Here are some common factors and reasons that can result in a disconnected OST file:** - The Exchange or Microsoft 365 account is deleted or disabled - Unstable or dropped internet connection during synchronization - The OST file is damaged - [Outlook profile corruption](https://sqmagazine.co.uk/outlook-windows-crash-exchange-bug/) - [Exchange Server settings](https://sqmagazine.co.uk/microsoft-exchange-hybrid-vulnerability/) were changed - Mailbox deletion or account removal ## What decisions should you take when your OST File gets disconnected, and Outlook won’t open? You can take the following decisions if your OST file is disconnected from the server. ### 1. Create a New Outlook Profile You have to first make sure that your mailbox is available on the server. You can do this by logging in via Outlook on the web (OWA). If you are able to log in without any issue, this indicates that there is an issue with your Outlook profile. In this case, you can create a new Outlook profile. Follow the instructions given below: - Open **Control Panel.** - Click on **User Accounts** and go to **Mail (Microsoft Outlook).** - Now click on **Show Profiles.** ![Mail Setup](https://sqmagazine.co.uk/wp-content/uploads/2026/03/mail-setup.jpg "Mail Setup") - Click on **Add** and enter a new **Profile Name**. ![New Profile](https://sqmagazine.co.uk/wp-content/uploads/2026/03/new-profile.jpg "New Profile") - Click **OK.** - Now enter the name and login credentials of your account. ![Account Setup](https://sqmagazine.co.uk/wp-content/uploads/2026/03/account-setup.jpg "Account Setup") - Click on **Next.** - After clicking **Finish,** the system will authenticate your login credentials and confirm that your Outlook profile is created. - Once the profile is created, select **Always use this profile** and choose the new profile. - Click on **Apply > OK.** ### 2. Convert OST File to PST If you can’t access your mailbox via Outlook web app, there is a chance that your mailbox has been deleted or removed from the mail server. In this situation, the only option left is to convert your offline data file to PST format. For this, you have to use a reliable [OST to PST converter tool](https://www.stellarinfo.com/convert-ost-to-pst.php), such as Stellar Converter for OST, to convert this orphaned file into PST. Additionally, this tool can save the OST file items in other common file formats, including MSG, RTF, EML, HTML, and PDF. **Here are the steps to convert your OST file to PST by using this tool:** - Go to the official website of Stellar Converter for OST. - Download and install the software. - Launch the software. - Now you will see two options: **List Profiles** and **Choose Manually.** ![List Profiles](https://sqmagazine.co.uk/wp-content/uploads/2026/03/list-profiles.jpg "List Profiles ") - Click on **List Profiles.** Select the default Outlook profile associated with the OST file. - Select the option – **Choose Mailbox Manually** if your OST file is located at a different location. ![Choose Mailbox Manually](https://sqmagazine.co.uk/wp-content/uploads/2026/03/choose-mailbox-manually.jpg "Choose Mailbox Manually") - After selecting the OST file, click on **Convert.** - Once the conversion is complete, you will see your mailbox data in a three-pane preview window. ![Three Pane Preview Window](https://sqmagazine.co.uk/wp-content/uploads/2026/03/three-pane-preview-window.jpg "Three Pane Preview Window") - Click on **Save Converted File** from the file menu. - Choose the file format as PST. ![Save Converted File](https://sqmagazine.co.uk/wp-content/uploads/2026/03/save-converted-file.jpg "Save Converted File ") - Click on **Browse** to select the destination to save your converted file. - Click **OK to save** the file. Once you have converted the OST file, import it into Outlook by using the Import/Export wizard feature to access the mailbox data. ## Conclusion If your OST file gets disconnected and Outlook won’t open, then the only option is to convert the OST file into PST format. For this, an OST to PST converter tool, such as [Stellar Converter for OST](https://www.stellarinfo.com/convert-ost-to-pst.php), can assist you. This tool can efficiently convert orphaned or inaccessible OST files of any size to PST format by maintaining the original folder structure and hierarchy. You can freely download this tool to convert your OST file and preview the data.