If you get an error message that the prXXmaster.dat (or other DAT) file is locked or the program is unable to read or write to it, there has been an interruption of, or conflict with, the TaxAct program (substitute XX for the tax year in use). This could be caused by security software, Windows rights and permissions, conflicts with user accounts, or different versions of Windows on a network. To resolve this issue, first restart your TaxAct program:

1. Open Task Manager (Ctrl + Shift + Esc).
2. In the Apps list, look for any item that says "TaxAct Application."
3. Right-click the item, then click End Task or End Process.
4. Make sure there are NO TaxActXX.exe items in the list. In Windows 10, you will need to also check the background processes part of the list. Be sure to scroll all the way down, beyond the Apps section. Repeat steps 3 and 4 for any instance.
5. Reopen TaxAct.

If the program opens successfully, you can exit Task Manager. If you get the same error again, repeat the steps above, restart your computer, then open TaxAct.

If the locked DAT file has a long string of random letters and numbers, you do not have to restart, delete that file.

If you continue to get the error, another program, such as your security software, may be keeping the file open in the background. You should configure your security software program to allow TaxAct files. Contact your security software provider, or an IT professional for detailed assistance.

Information for TaxAct Enterprise Edition

If you have TaxAct networked, you may need to end all processes on every computer that is currently connected and sharing the Client Data folder. This will require going to each computer and using the steps above. You may need to shut down each of the computers. If you have a host computer (you are not using a dedicated server), do all the steps on it last, including rebooting.

Network setups that can contribute to this problem:

• If you have networked TaxAct on a host computer, mapping that computer's drive to itself as another drive designation.
• If you have shared a folder on a higher level than Client Data\[Practice ID] or the whole C: drive of the host computer.
• If you are sharing the program .exe file in a server/client type setup.

Make sure you have installed the TaxAct program on each computer you are using and that you are only sharing the Client Data folder. If you are using a dedicated server, use only a folder for the Client Data to share with the computers. Do not share the program executable file (.exe) by running it off the server for all machines.

Make sure you do not have more than one user account logged on to any one computer with the program open at the same time.

If all the above fails, for network or a single computer

Delete the prXXmaster.dat file by following these steps:

• All TaxAct processes must be ended with Task Manager. 

• Then, using the Windows Explorer, navigate to the Client Data folder, and delete the file.

• The program will be able to import preparer master information from a previous year, if available.