How to fix Microsoft Office error 30088-45 in Windows?

Error code 30088-45 is an Office Click-to-Run setup error that most often appears when you install Office after removing an older version. Restart the PC and check that drive C: has free space, then remove every Office with Microsoft's uninstall troubleshooter and install again. If Office still opens and the code came during an update, run Online Repair instead.

Facts checked on 15 October 2026. Steps written for Click-to-Run versions of Microsoft 365, Office 2016 to 2024 on Windows 11 (25H2 and 26H2) and Windows 10 22H2, read against Microsoft's support pages.

What error code 30088-45 means in Microsoft Office

Every current desktop Office, from Office 2016 to Office 2024 and Microsoft 365, is installed, updated and removed by Click-to-Run. When that setup cannot finish, it shows a window that says Something went wrong and a code line such as Error Code: 30088-45. The code belongs to setup, not to Word, Excel or Outlook.

• The typical case. On Microsoft Q&A, a Windows 11 Home user had Microsoft 365 from work and a standalone Office 2016, removed all of them, bought Office 2021 and could not install it. Every try ended with error code 30088-45. The firewall was not the cause.
• Microsoft's answer there named two possible causes: leftover information from old Office versions, and damaged Windows system files. That order is the order of the fixes below.

What causes Office error 30088-45, from the most common to the rare

Microsoft names no single cause for 30088-45. The ranking below is our reading of Microsoft's answer on the 30088-45 report and of its own pages for the 30088 family. It is an order of likelihood, not a statistic.

How to fix error code 30088-45 when you install or update Office

Fix 1 and Fix 2 solve the common case, a new Office that will not install after an old one was removed. Fix 3 is for an Office that is still installed. Fix 4 to Fix 7 are for the rarer causes, in order of cost.

Fix 1. Free space on drive C:, restart Windows and run setup again

5 to 10 minutesLow riskEveryone first. Above all when drive C: is nearly full or you have not restarted since you removed Office.

Microsoft tells you to free up drive space first for the 30088 setup errors. A restart also ends any Office process or half-finished removal that setup would run into.

1. Close the setup window with Close.
2. Open File Explorer and select This PC. Look at the bar under Local Disk (C:). If it is red, free some space.
3. Select Start > Settings > System > Storage and use Cleanup recommendations. All steps: Free up disk space and delete temporary files.
4. Select Start > Power > Restart. Use Restart, not Shut down.
5. Sign in at microsoft365.com with the account that owns Office and start the installation again.

Fix 2. Remove every Office with Microsoft's uninstall troubleshooter, then install again

20 to 45 minutesRead the warningYou removed an older Office before this installation, had more than one version, or Fix 1 did not help.

Microsoft's answer to the 30088-45 report points to leftover information from old Office versions. The troubleshooter clears Microsoft 365, Office 2021, 2019 and 2016 so that the new setup starts from nothing. It is also Microsoft's first solution for 30088-1015.

1. Sign in to Windows with an administrator account.
2. Open Microsoft's uninstall troubleshooter link.
3. Select Open when the browser says This site is trying to open Get Help.
4. Follow the prompts. When it asks which versions to remove, select all of them.
5. Restart the PC when you are prompted.
6. Check Settings > Apps > Installed apps (Windows 10: Apps > Apps & features) for any Office that is left.
7. Install Office again from microsoft365.com with the account that owns it.

Fix 3. Run Online Repair when Office is still installed

15 to 30 minutesLow riskOffice still opens, and 30088-45 appeared during an update or when you tried to add or change an app.

For the update error 30088-26, Microsoft's first solution is to repair Office from Windows and to choose Online Repair to make sure everything gets fixed. It replaces damaged Click-to-Run files without a full removal.

1. Right-click Start and select Installed apps (Windows 10: Apps and Features).
2. Find Microsoft 365 or your Office product, select the three dots or the entry, and choose Modify.
3. In How would you like to repair your Office programs?, select Online Repair, then Repair.
4. Follow the prompts, keep the PC online, and restart when it is done.
5. Run the update again from File > Account > Update Options > Update Now in Word.

Quick Repair works without a connection and is faster, but Microsoft recommends Online Repair for setup and update codes. Both options with every screen: How to repair Microsoft 365 or Office.

Fix 4. Turn off the proxy and install over a plain connection

10 to 30 minutesLow riskYou install at work, at school, with a VPN or behind a proxy, or setup stops while it downloads.

Microsoft lists proxy settings, a limited network and a weak connection as causes of the 30088 install error 30088-1015. Its offline installer downloads Office first and installs it without the live connection that a proxy can break.

1. Turn off any VPN app until Office is installed.
2. Select Start > Settings > Network & internet > Proxy.
3. Under Manual proxy setup, turn Use a proxy server off if you set it on for testing. On a work PC leave it to IT.
4. Use a cable instead of Wi-Fi if you can, or try another network such as a home connection or a phone hotspot.
5. Run Office setup again.

• Still stops on download? Microsoft's page Use the Office offline installer has a tab for each Office version. It may help bypass proxy, firewall, antivirus or connection problems.
• On a work or school network the limit can be on purpose. Microsoft's own advice is to ask IT, or to install at home and then use Office at work as usual.
• Is the connection itself sound? Check it once: How to check your internet connection in Windows.

Fix 5. Remove Office leftovers by hand when the troubleshooter misses them

30 to 45 minutesRead the warningThe uninstall troubleshooter finished or failed, you had Office 2024, or setup still finds an old Office.

Microsoft's own tip for a troubleshooter that does not remove everything is to uninstall Office by hand. That is the case Microsoft's answer on 30088-45 describes: residual information from old versions that setup still reads.

1. Open Settings > Apps > Installed apps and remove every entry that starts with Microsoft 365, Microsoft Office or Office, including language packs.
2. Restart the PC.
3. Open Microsoft's page Manually uninstall Office and pick the Click-to-Run tab.
4. Follow its steps for the Office folders, the scheduled tasks and the registry keys, in the order Microsoft gives.
5. Restart the PC and install Office again as in Fix 1.

We walk through the same Click-to-Run cleanup, with each folder and key, in our guide to Office installation error 30015-25. The parts are the same for 30088-45.

Fix 6. Pause a third-party antivirus for one installation

10 minutesLow riskYou use a security suite other than Microsoft Defender, and every fix above failed.

Microsoft lists antivirus and firewall software among the things that can stop Office setup with a 30088 code. Pausing one for a single test shows whether it blocks setup.

1. Download the Office installer first, while protection is still on.
2. Pause the security app for the shortest time it offers: Turn off Microsoft Defender protection for a moment.
3. Run the Office installer.
4. Turn protection back on right after setup ends.

If setup works only while the app is paused, add the Office installer to the app's exceptions or ask its maker for help. The fix is in the security app, not in turning it off.

Fix 7. Repair Windows system files, then Windows itself

20 minutes to 2 hoursRead the warningOffice is fully removed, Fix 1 to Fix 6 did not help, or other programs fail to install too.

Microsoft's answer on the 30088-45 report names damaged Windows system files as the second possible cause, and suggests an in-place repair of Windows 11 that keeps files and apps.

1. Run the system file check and DISM once: Run DISM and SFC to repair Windows system files.
2. Restart the PC and run Office setup again.
3. If it still fails, repair Windows with an in-place reinstall that keeps your files and apps: Reinstall Windows without losing files.
4. Install Office after the repair, before you install other software.

If error 30088-45 is still there: what to check and what to send

The setup window shows only the code. Click-to-Run setup keeps text logs in the %temp% folder of the user who ran it, and Windows records failed installs in Event Viewer. We could not confirm from Microsoft which log line belongs to 30088-45, so read them as a hint.

1. Run setup once more and note the time.
2. Press Win + R, type %temp% and press Enter. Sort by Date modified, newest first.
3. Open the newest .log files and search with Ctrl + F for 30088, then for error.
4. Press Win + R, type eventvwr.msc and look under Windows Logs > Application for errors at that time.

• A managed work or school PC may block installs by policy. Only IT can change that.
• A licence or account problem shows a different message, about activation or the account, not a 30088 code. Check that the Microsoft account shows your Office at account.microsoft.com.
• What to send to Microsoft support: the full code, the Office product and year, and whether it happened on install, update or removal. Add the Office versions the PC had before, the Windows version from Settings > System > About and the newest setup log.

How to avoid error 30088-45 the next time you change Office

Almost every report of this code starts with a switch between Office versions. Removing the old one the supported way and restarting before the new setup avoids most of it.

Frequently asked questions

What does error code 30088-45 mean?

It means Office Click-to-Run setup could not finish. The window says Something went wrong and shows Error Code: 30088-45. Microsoft does not publish what the 45 stands for, and it has no support page for this exact code. In the report on Microsoft Q&A, the user saw it when installing Office 2021 after removing Microsoft 365 and Office 2016, and Microsoft's answer pointed to leftovers of old Office versions and, less likely, damaged Windows files.

How do I fix error 30088-45 when installing Office?

Free space on drive C: and restart the PC, then run setup again (Fix 1). If the code returns, remove every Office with Microsoft's uninstall troubleshooter, which opens in the Get Help app, restart and install again (Fix 2). If you had Office 2024, remove it in Installed apps, because the troubleshooter cannot remove that version yet. Leftovers after that are removed by hand with Microsoft's manual uninstall steps (Fix 5).

Is error code 30088-4 the same as 30088-45?

It is the same family of Office setup errors, and the fixes on this page apply to it too. Microsoft does not explain the second number for 30088-4 or 30088-45, and it has no separate support page for either one that we could find. If your code is 30088-26 or 30088-29 and you were updating Office, start with Online Repair (Fix 3), which is Microsoft's first solution for 30088-26.

Does error 30088-45 delete my documents?

No. The error stops setup and touches no files. The fixes do not delete documents either: Microsoft says uninstalling Office removes only the apps, not the files, documents or workbooks you made with them. A manual cleanup (Fix 5) removes Office settings and cached sign-ins, and Outlook data files may sit near those folders, so copy any .pst file first. Mail in Microsoft 365, Outlook.com or Gmail stays on the server.

Can I get error 30088-45 when uninstalling Office?

Yes, people search for 30088-45 on uninstall too, because removal also runs through Click-to-Run. When Office will not uninstall from Settings, use Microsoft's uninstall troubleshooter instead (Fix 2). If that fails or the product is Office 2024, remove what you can in Installed apps and follow Microsoft's manual uninstall steps (Fix 5). Restart before you install anything again.

Should I turn off the Windows firewall to fix 30088-45?

No, not for good. Microsoft lists antivirus and firewall software among the possible blockers for 30088 install errors, and it says to turn them off only for the test and back on right after. In the 30088-45 report on Microsoft Q&A, the user had already ruled out the firewall. Try the fixes for leftovers and the network first. If you still want to test, pause a third-party security app for one installation only (Fix 6).

Where is the Support and Recovery Assistant that old answers mention?

Older answers, including the one on the 30088-45 report, link to Microsoft Support and Recovery Assistant. Its uninstall job now runs in the Get Help app. The Uninstall button on Microsoft's 30088 pages opens Get Help, which removes Microsoft 365, Office 2021, Office 2019 and Office 2016. It needs Windows 10 or higher and currently cannot remove Office 2024.

What are ai30088 and error code 30045-4?

We found no product or Microsoft code called ai30088. If you meant the Office code 30088, this page covers that family. Error code 30045-4 is a different Office setup family, not a spelling of 30088-45, so this page does not decode it. The general steps are similar, a full removal with the uninstall troubleshooter and a clean installation, but check Microsoft's page Troubleshoot installing Office for its own advice.

Is 30088-45 caused by Windows 10 being out of support?

Not directly. Windows 10 left support on 14 October 2025, but Microsoft's 30088 pages and its uninstall troubleshooter still list Windows 10 as supported for these steps, and the 30088-45 report on Microsoft Q&A came from Windows 11 Home. Office 2016 and Office 2019 also reached the end of support on that day. They still install and run, but get no more security updates.