How to Fix a Corrupted QuickBooks Data File

When you have problems with your QuickBooks® data file, it can be upsetting and time consuming to fix. Yet, based on some good practices and warning signals, you can, hopefully, prevent a corrupted file.

You’ll want to get familiar with the Product Information Window (press F2 or Ctrl-1). You’ll need that for some of the items listed below.

  1. Keep current with the update patches. Your release number can be found on the first line in the Product Information window. These patches fix problems users have found. The article below gives more detail on learning which release patch you are using, what the latest patch is and the Intuit® Product Update website.
  2. Monitor your file size (found in the Product Information window). QuickBooks Pro and Premier run fine as large as 250 MB, but you may see decreased performance once you are at 500 MB or higher. For QuickBooks Enterprise, the optimum is around 500 MB and you may see issues around 750 MB. Intuit will tell you that you can have larger data files, which is true, but performance may not be as you like and your risk for problems starts to increase. To convert the kilobytes to megabytes, divide by 1024 or go to By the way, there are tools that can shrink your data file and make it work great, as well as tools to extract the last couple of years’ worth of data.
  3. Check your database file fragments monthly (also found in the Product Information window). As your computer fills up and data is being written, fragmentation occurs over time. It’s like throwing stuff into your closet instead of neatly putting things away. You want the number to be below 10; 100 could indicate some serious problems.
  4. Monitor your list size (found in the Product Information window). In QuickBooks Pro and Premier, there are list limits, and QuickBooks will not warn you if you are near your limit – inactive list items do count in this list. Here’s an Intuit support article on the topic.
  5. Make a verified backup monthly from WITHIN QuickBooks. Many of you now just have your data files backed up automatically, which is good, but not good enough with QuickBooks. A log file gets created and continues to grow in size, impacting performance and risking corruption – unless you back up. This file is what Intuit uses if you ever send your file to Data Recovery; verification looks for errors, so you can catch problems sooner and fix them.
  6. If you are on a network, you want the network hard-wired, not wireless. With wireless, the risk increases for dropped connections, which cause problems with your data file. If you find your network is hard-wired and you have lost connection at some point, there may also be problems.

If you find your file is at risk, then there are several steps you can take to improve the health of your data file, but that’s a topic for another day.