Eaglesoft “Hexadecimal Value 0x00 Is an Invalid Character” Error: Causes and How to Fix It

Short answer: This error usually means a settings file that Eaglesoft keeps for the Windows user on that computer has become damaged. The message names the file, often a user.config file in the user’s AppData folder, and says it contains an invalid character (0x00, a blank “null” character). It is typically limited to one workstation or one Windows user, and the practice database itself is not affected. Note the full error text, close Eaglesoft, and call your IT provider or Patterson support.

What the error means

Like many Windows programs, Eaglesoft saves some settings in a small file for each Windows user on each computer. If that file is damaged, for example because the computer lost power or crashed while the file was being saved, the file can end up filled with blank characters. When Eaglesoft tries to read it, Windows reports that a “hexadecimal value 0x00” is an invalid character, usually with the file path and a line number. Because this file belongs to one Windows user on one computer, other workstations normally keep working.

Likely causes

• The computer was turned off or lost power while Eaglesoft was open.
• Windows crashed or was forced to restart while Eaglesoft was saving settings.
• The disk is failing or full, so the file was not written correctly.
• Security software interfered while the file was being written.

What to check first

1. Write down the full error message, including the file path and line number. Take a photo if you cannot copy it.
2. Close Eaglesoft completely on the affected computer.
3. Check whether other workstations work. If they do, the problem is local to this computer, which is good news.
4. Try logging in to Windows as a different user on the same computer, if your office has one. If Eaglesoft opens for that user, the damaged file belongs to the first user’s profile.
5. Note what happened recently: a power cut, a forced restart, an update.

How to fix it

[[TECH INPUT NEEDED: actual fix steps from tickets for the “hexadecimal value 0x00” user.config error, e.g. which file to rename, where, and what Eaglesoft rebuilds on next launch]]

How to stop it happening again

• Put workstations, not only the server, on a battery backup if power cuts are common in your building.
• Close Eaglesoft before shutting down a computer.
• Replace drives that report errors. A damaged settings file can be an early sign of a failing disk.

Frequently asked questions

Is our Eaglesoft data damaged?

This error points to a per-user settings file on one computer, not the practice database on the server. Other workstations usually work normally.

Should we reinstall Eaglesoft?

No. Reinstalling is rarely needed for this error and can cause other problems. Call IT or Patterson first.

Why did it happen after a power cut?

If a computer loses power while a file is being saved, the file can be left incomplete or filled with blank characters, which is exactly what this error describes.

Still down? Call (716) 463-5111

If Eaglesoft will not open on a workstation, call Buffalo IT Services at (716) 463-5111. We support the computers and network Eaglesoft runs on, alongside Patterson support. See our Eaglesoft IT support page.