A few of the difficulties with QuickBooks software verification
QuickBooks repair error
Plus some errors even though you simply updating QuickBooks accounting software
Company files are only corrupted
Damaged QuickBooks database
Approaches to Resolve the QuickBooks Error Code C=51
Solution One:-
In the first solution, you need to simply update the QuickBooks software towards the latest release so that you can just be rid of “QuickBooks Error C=51.

Solution Two:-
First of all, just close all of the tabs in QuickBooks accounting software.
And from then on, simply power down the QuickBooks software.
Now, in this step, you need to just reopen the QuickBooks application and just perform the same work with which you received “error code C=51”.
And lastly, you need to simply repair all the data in a suitable and right format.
Solutions Three:-
Within the third solution, whilst you simply restoring complete backup files, so, if that's the case, it is always suggested to use probably the most modern QuickBooks software version.

Solution Four:-
In the very first step, after restoring all the backup files, you must simply press the ctrl + C and then just move them in a new folder.
Now, following the backup is simply made, then just verify the file size as it always should really be a lot more than 6MB.
And then, just do a right-click in the file and simply select the properties option.
In this task, in the event that complete backup file is merely significantly less than 6MB then it is the wrong backup file.
At last, you need to just make a complete backup file again.
Solution Five:-
First, simply download the best QuickBooks file doctor tool.
After completing the initial step, you have to just check all of the files having this QuickBooks error.
Not only that, simply use the great tool and then just see in the event that error code C=51 still exists.
Also Read:- QuickBooks Error 6010

In Conclusion
In case, if the QuickBooks error code C=51 is not fixed simply by following the above solutions, you'll be able to easily get amazing support from the QuickBooks help service by simply dialing our toll-free QuickBooks online support phone number . Because our QuickBooks professionals are highly certified and specialists in QuickBooks software, plus they always available for all of the QuickBooks users.