Office installation error “Couldn’t start office installation error code 0-1018 (0)” appears when there are registry leftovers from a previous installation, or when another Office installation is already in progress on the same computer.
This guide explains the causes and the steps to fix it.
What Causes Error Code 0-1018 (0)?
Multiple installation instances — this error commonly appears if the Office installation program was started more than once, creating multiple instances running at the same time.
Registry leftovers — leftover registry entries from a previous Office installation can interfere with a new install, requiring the old data to be cleaned up first.
System issues — corrupted files, a damaged system registry, or malware and spyware can also trigger this error.
Bit version mismatch — if your previous Office installation was 64-bit, trying to install a 32-bit version (or vice versa) will show this same error, since Office requires you to stick with the existing bit version or uninstall it first.
Here’s how to fix it:
Stop any other Office installation in progress
Open Task Manager, look for any ongoing Office installation process, and end it. Office can only install correctly with a single active installation instance running — running more than one at once triggers this error.
Clean up registry leftovers from a previous installation
If old registry entries are involved, they need to be cleaned up before a new installation can proceed. Editing the registry carries risk, so back it up first, or get guidance from a technician before making changes.
Match the bit version to your existing installation
To install the 64-bit version (if your previous install was 64-bit): it will work alongside your existing 64-bit applications, so proceed by selecting “Install 64-bit.”
To install the 32-bit version instead: select Cancel, uninstall your existing 64-bit Office applications first, and then start the 32-bit installation again.
Scan for malware and check system files
Run a full antivirus scan to rule out malware or spyware interfering with the installation, since corrupted files can also cause this error.
Still Not Resolved?
If you need help installing the correct bit version, or you’re still getting this error after trying the steps above, our experts are here to assist you — Chat with a specialist — and can take a look at your specific setup, including via remote assistance if needed.
We are an independent technical support provider and are not affiliated with, endorsed by, or sponsored by Microsoft.
FAQ
What causes Office error code 0-1018 (0)?
It’s usually caused by multiple installation instances running at once, registry leftovers from a previous install, corrupted system files, or a mismatch between the 32-bit and 64-bit Office versions.
Can I install 32-bit Office over a 64-bit installation?
Not directly — you need to uninstall the existing 64-bit Office applications first, then start the 32-bit installation fresh.
Is it safe to edit the registry to fix this error?
It can help remove leftover entries causing the conflict, but back up the registry first and proceed carefully, or get expert guidance if you’re unsure.
Can malware cause this Office installation error?
Yes. Malware, spyware, or corrupted system files can interfere with the installation process and trigger this same error message.
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