can't update to v26 error code 127

Error 127 is an installer failure. It’s usually caused by a corrupted Creative Cloud download, not enough free space, temp folder permissions, antivirus software, or damaged Visual C++ runtime components.

Try the following:

1. Cancel the update in Creative Cloud > Updates, quit all Adobe apps, and restart your computer. Wait a few minutes before trying again.
2. Check the free space on your system drive. The update extracts through the system temp folder, even if Premiere is installed on another drive.
3. Sign out of Creative Cloud, quit it, reopen it, sign back in, and retry the update.
4. Temporarily disable any antivirus or security software, run the update, then turn it back on.

If it still fails, update the Creative Cloud app itself first. Go to Creative Cloud > Apps > More actions > Check for updates. An outdated Creative Cloud app can fail to download the Premiere installer correctly.

https://helpx.adobe.com/in/creative-cloud/apps/troubleshoot/install-update-issues/app-update-errors.html