As per Intuit, QuickBooks error code 6000, 304 is mostly encountered at time of opening the company file (.qbw).
Triggers to QuickBooks error 6000, 304:
QuickBooks company file may be damaged.
Insufficient disk space
To fix QuickBooks error 6000, 304:
Relocate the company file to another disk.
Free some space in the disk that has the company file.
QuickBooks error 6000, 304 still bothering you?? Feel free to connect with the Experts of QuickBooks enterprise support by dialing +1-888-485-0289.