In order to eliminate the QuickBooks Error 6129, you would have to follow these steps I found in an amazing blog. Check them out.
Restart your system in Safe mode. Disable the anti-virus or anti-malware software in your system and create a new Company File. Now restart the system in the normal mode and open QuickBooks with your Company File.
More solutions follow in the blog, do read them and if none of them solve your issue, call us on xxx-xxx-xxxx to get live assistance from our expert support staff.