You can only merge files with the same accounting type and with identical accounting plans. More information are available at the Merge file page.
Causes
You tried to merge two different files, for example:
- A double-entry accounting file and a Income and Expenses file
- A double-entry accounting file with VAT and a double-entry accounting file without VAT
- A double-entry accounting file with multicurrency and a double-entry accounting file without multicurrency
Solutions
- Verify what accounting file you have with the File Info command from the Tools menu.
- With the Convert to new file command from the Tools menu, you can make change one file's type so the two files to be merged are of the same kind.