Stumbled on QuickBooks Error Code C=51?  So, this error can be caused due to:  Alterations in txList.  How to fix Error C=51? Creating the backup of the company file.  Create a backup of your company file and also make sure that size of the file is greater than 6MB. This will fix Error C=51.  And that’s all!! If you feel you are stuck on anything, you can reach...