Resolve Windows "not a valid floating point value" Error

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What is causing this Error?

The error occurs when the software expects a Windows region/format set to US (or UK, depending on the app), and the decimal or digit grouping symbol doesn't match what the program expects. Many older applications (accounting, POS, engineering, and reporting tools) are hardcoded to expect. as a decimal separator if your Windows region uses, Instead (common in much of Europe), the app throws this error trying to parse a number.

How do I resolve this Error?

In Windows 10

US users

Select the Start button, and then select Settings.
Select Time & Language.
Select Region in the menu on the left.
Adjust the Country or Region to the United States.
Restart your system to allow this to take effect.

All other users

Select the Start button, and then search for Control Panel.
Select Region, and then Additional settings.
Change the decimal symbol to ‘.’ (apostrophe, period, apostrophe) and digit grouping to the same ‘.’.
Apply changes and try again.

In Windows 7

Select the Start button, and then select Control Panel.
- View by: Small icons.
Select Region and Language from the list.
In the Formats tab, set the Format to the United States.
In the Location tab, set Current Location to the United States.
In the Administrative tab, select Change system local.
- Change the current system locale to the United States.
Now in the Administrative tab, select Copy settings.
- Copy Settings to the following:
  - Welcome Screens and System Accounts
  - New user accounts
Restart your system to allow this to take effect.

In Windows 11

Open Settings → Time & Language → Language & Region.
Under the Regional format, select either:
- Switch to English (United States) (or whatever region the software expects — some apps specifically want English (UK) instead),
  or
- Select Additional settings and manually change the Decimal symbol to . and digit grouping symbol to ,.
Restart the app (sometimes a full reboot is needed) since some programs only read regional settings at startup.

If changing your whole system region isn't ideal, you can also just fix the decimal/grouping symbols under Region → Additional date, time & regional settings → Change date, time, or number formats → Additional settings without switching the entire locale.