Microsoft 365 is one of the most widely used productivity software suites for businesses of all sizes. From email and file storage to internal messaging apps and spreadsheet management, it’s easy to understand why so many organizations rely on it daily.
But like any cloud-based platform, it’s not immune to occasional hiccups. Whether it’s a login error in Outlook, problems installing apps, or OneDrive refusing to sync, even minor issues can severely disrupt productivity.
Fortunately, with the right strategies, addressing these problems can be a simple process. In this guide, we explain how to fix common Microsoft 365 issues to help you get back on track faster.
Microsoft 365 Applications
Microsoft 365 (formerly known as Office 365) is a cloud-based subscription service that offers a suite of tools designed to help businesses communicate, collaborate, and stay productive from virtually anywhere. Over 2 million companies worldwide use Microsoft 365 to streamline workflows and collaborate.1
Some of the most commonly used Microsoft 365 applications include:
- Word: word processing and document creation
- Excel: spreadsheets
- PowerPoint: slide presentations
- Outlook: email, calendar, and contact management
- Teams: text chats, video conferencing, and file sharing
- SharePoint: file storage and management
- OneDrive: online storage service
These tools are designed to streamline operations and boost productivity for businesses of all sizes. However, as helpful as Microsoft 365 products are, organizations that rely on them every day can occasionally encounter technical issues.
How to Fix Common Microsoft 365 Issues
Even though Microsoft 365 is designed to make work easier, it’s not uncommon for users to run into occasional problems. These tech hurdles can become especially common as organizations grow, onboard new employees, or adjust security settings.
The good news? Many Microsoft 365 issues are well-documented and can be resolved with a few targeted steps. Below, you’ll find the most common problems users face in Microsoft 365 and practical troubleshooting tips for each one.
1. Can’t Install Microsoft 365 Apps
One hurdle users encounter is not being able to install Microsoft 365 apps like Word, Excel, Outlook, or Teams on their devices. This can be especially frustrating when setting up a workstation for a new employee or transitioning to a new computer.
Stalled progress bars, error codes, or installations that appear successful but fail to launch can be frustrating and halt operations. To solve these common installation issues, try the following strategies:
- Check system requirements: Make sure the device meets the minimum system requirements for Microsoft 365.
- Remove previous installations: Go to your system settings and uninstall any older versions.
- Run as Administrator: If you’re on a work device, right-click the installer and choose Run as Administrator to ensure you have the necessary permissions.
- Switch to a wired (Ethernet) connection: This will ensure your network connection is stable and potentially increase installation speed.
- Check your subscription status: Make sure your license is active and assigned to your account via the Microsoft 365 Admin Center (if applicable).
- Disable antivirus/firewall temporarily: Some security programs can block installations. Just be sure to turn them back on afterward.
By following these steps, most Microsoft 365 apps can be installed effectively without trouble. If the issue persists, contact the True IT support team, and we would be happy to assist.
2. Can’t Sign In to Microsoft 365 Account
Sign-in problems are some of the most common issues that occur with Microsoft 365 products, and the most disruptive. Whether you’ve forgotten your credentials, received a confusing error message, or recently changed devices, being locked out of your account can bring work to a halt.
Lost Account Access
Sometimes users simply forget their password, lose access to their recovery email, or get locked out after too many failed login attempts.
If you can no longer access your Microsoft account, try these methods to recover it:
- Reset your password: Select the blue “Forgot password?” button and follow the prompts to reset your password.
- Forgotten username or email: If you can’t remember the username or email associated with your account, look up your account using Microsoft’s username recovery tool.
- Password doesn’t work: Use Microsoft’s Sign-in Helper Tool if you’re using the correct password, but it’s no longer working.
- Multi-factor authentication (MFA) issues: If you’re prompted for MFA but don’t have access to your verification method, your account admin should be able to reset your MFA settings.
Error 400 When Signing In
If you’re using the right credentials but keep getting an “Error 400” or “Bad Request” message every time you try signing in, this typically indicates a problem with the request being sent to Microsoft’s servers.
To solve this issue, try to:
- Clear your browser cache and cookies: This often resolves the error right away.
- Try a different browser or incognito/private mode: This helps determine if the issue is browser related.
- Use the web app: If you’re unable to sign in via a desktop app, test access through the website to isolate the issue.
- Check the Microsoft 365 Health dashboard: This will tell you if there are any known outages affecting sign-in within your organization.
If problems continue, it could indicate a deeper account or configuration issue that should be escalated to your Microsoft 365 admin or a professional IT provider like True IT.
3. OneDrive Files Aren’t Syncing
OneDrive is a cloud-based storage service designed for storing, sharing, and backing up files across devices. However, syncing issues can prevent files from uploading, updating, or appearing across platforms.
Whether you see a red “x” on a file or notice documents aren’t updating between devices, it’s usually tied to a connection or configuration problem. Here are a few simple fixes to try:
- Specific files aren’t syncing: If specific OneDrive files aren’t syncing, this could be because it’s open or being used by another application. Try closing the file and waiting for OneDrive to process the update before resuming your work.
- OneDrive can’t access the file: If OneDrive can’t access the file you’re trying to sync, make sure you have Read/Write permission. Edit permission is required for uploading files to OneDrive.
- Your device is running low on storage: If your PC is running out of space, you may experience difficulties with file syncing. Try clearing up storage by emptying the recycle bin, deleting unnecessary files, or uninstalling apps you no longer use.
- Your cloud storage is running out: Your Microsoft account has a set amount of cloud storage depending on your subscription tier. If you’re running out of cloud storage space, you won’t be able to edit, upload, or sync new files to your OneDrive.
- Unstable internet connection: Network connectivity issues can interfere with OneDrive file synchronization. Make sure your connection is strong and stable.
While not every sync issue has a quick fix, these steps can help resolve the most common problems to keep your files accessible and secure.
4. Outlook Keeps Asking for Password
One of the more frustrating Microsoft 365 issues is when Outlook repeatedly prompts you to enter your password, even after you’ve successfully logged in. This looping behavior can interrupt workflow and is often a sign of a deeper issue with account authentication or configuration.
Here are some possible fixes for frequent password prompts in Outlook:
- Restart Outlook and your computer: It’s a simple step, but sometimes a fresh start can resolve minor glitches.
- Check for updates: Install any pending Outlook or Windows updates to keep everything running smoothly. Reopen the app and see if the issue persists.
- Switch to a stable network: A slow or unstable network may cause Outlook to disconnect from the mail server.
- Create a new Outlook profile: A corrupt Outlook profile can cause Outlook to stop remembering your password. Creating a new mail profile in the Control Panel and reconfiguring your email account in the new profile may solve the issue.
- Temporarily disable antivirus software: Some antivirus programs integrate with Outlook to scan emails and attachments in real-time. Sometimes they can cause performance issues or incorrectly mark legitimate files as malicious and block access. Try temporarily disabling antivirus software and check if the issue stops.
- Clear cached credentials: Try removing any outdated or incorrect credentials saved on your computer. Restart your computer and enter your password when prompted.
If the issue persists, it’s best to contact professional IT support for deeper troubleshooting.
5. Accidentally Deleted a File in OneDrive
There’s nothing more gut-wrenching than accidentally deleting the wrong file. Fortunately, if you’ve accidentally deleted a file in OneDrive, you may be able to recover it.
Below are some ways to recover a deleted file in OneDrive:
- Check the OneDrive Recycle Bin: Not all deleted files are permanently wiped right away. Check the Recycle Bin in OneDrive and restore the lost file from there.
- Check your computer’s Recycle Bin: If you’re syncing files to OneDrive, actions completed locally (like on your computer) are also reflected in the cloud, and vice versa. Try checking your computer’s Recycle Bin and recovering the file.
- Restore to a specific point in time: The Restore your OneDrive feature allows you to undo all actions within the last 30 days. This means you can recover any deleted, corrupted, or infected files by restoring your entire OneDrive to a previous point in time.
- Contact Microsoft Support: In some cases, Microsoft Support can recover files even after they’ve been emptied from the Recycle Bin, but only within a 14-day window.
To avoid accidental deletions in the future, consider turning on version history for critical files and enabling alerts for shared folders.
6. Out of Storage Error Message
All Microsoft 365 accounts have a set amount of storage, depending on your subscription. Running out of storage, whether in OneDrive, Outlook, or SharePoint, can stop you from sending emails, uploading files, or syncing data across devices. These limits vary by plan, but once you hit them, the disruptions are immediate.
Below are some tips for troubleshooting storage-related Microsoft 365 issues:
- Empty your Recycle Bin: Even after you delete a file, it will be stored in the Recycle Bin for up to 93 days. Clear your recycling bin to free up storage space.
- Check for hidden files: Hidden files or folders still take up space, even if they’re not readily visible. Go through hidden items and delete what you no longer need.
- Manage version history: OneDrive and SharePoint automatically create versions of files as backups. If you’ve completed a considerable amount of work on a large file, Version History can take up a lot of space. Managing Version History can free up some room.
- Delete Outlook attachments: Although email storage is separate, attachments in Outlook can still impact your Microsoft storage. Try deleting old attachments to get more space.
- Manage shared files: Folders shared with you can also contribute to storage usage. Remove shared folder shortcuts that you don’t need anymore.
If you’re unsure what’s taking up the most space or need to increase storage across your Microsoft 365 account, contact the True IT team, and we can help review storage metrics and adjust plan settings accordingly.
Get Microsoft 365 Support for Your Business from True IT
If your business is experiencing frequent problems with Microsoft apps, you’re losing out on incredible productivity potential. As a recognized Microsoft Partner, True IT offers Managed Microsoft 365 services to help your organization navigate these tools and take full advantage of their benefits.
From setup and configuration to training and beyond, we’re here to help streamline operations and eliminate roadblocks so your business can thrive. Contact True IT online today to schedule a FREE consultation and get support from experts who understand how to keep your systems running efficiently.
References
- Statista. (2025, February 27). Number of Office 365 enterprise subscribers worldwide 2025, by country. https://www.statista.com/statistics/983321/worldwide-office-365-user-numbers-by-country/
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