Once your data is prepared to be used in Simply Accounting Online" meaning
This warning means your company file is about to be converted for the online edition and will no longer open in the Windows desktop program.
You are seeing this message:
Once your data is prepared to be used in Simply Accounting Online, you can no longer open it with Simply Accounting for Windows.
Despite the wording, this is not an error. It is a one-way-door warning. Simply Accounting is telling you that the conversion it is about to run will rewrite your company data into the format the online service uses. After that, the desktop program for Windows cannot open the file again. The software is asking you to confirm you understand the step is permanent before it proceeds.
What the message actually means
The desktop and online editions store data differently. Moving to the online service means your file is converted into that other format. There is no built-in command that converts it back. Once the preparation finishes, your Windows installation will treat the converted data as belonging to a different product.
The message appears before the change, not after. That matters. Until the conversion actually runs, your data is still a desktop file and still opens normally in Simply Accounting for Windows.
Why the software warns you this way
The conversion is deliberately one-way. The online service and the desktop program do not share a common file format, so the vendor chose not to promise a return path. The warning exists so nobody converts by accident and then discovers they cannot go back.
It also protects the vendor from support disputes. If you confirm and continue, you have acknowledged the desktop copy will stop working.
What to do before you continue
Stop and take a backup first. This is the single most important step. A backup taken before the conversion is your only way back to a working desktop file if you change your mind later. Keep it somewhere safe and separate from the machine, and do not overwrite it.
Check that everyone who uses the data is on board. If an accountant or another user still works in the Windows program, converting will cut them off. Agree on the timing before anyone clicks through.
If you are converting because you were told to, but you actually want to keep working in desktop, cancel now. Nothing has changed yet.
Can the data come back to desktop?
Not through any built-in command. If you have already converted and need the data back as a desktop company file, or moved into QuickBooks instead, that is a conversion job rather than a menu option. Our engineers handle both directions, including converting Simply Accounting to QuickBooks and repairing damaged Simply Accounting databases. Whether a return to desktop is possible depends on the file and on what the conversion changed, so we evaluate before promising anything.
A useful next step
Before you click past the warning, make a fresh backup and test that it restores. If you have already converted and need the data back in a desktop product, send us the file for a free evaluation and quote. We will tell you what is recoverable before any work starts.