[SalesForce] ‘No data to import’ when importing .stf with Translation Workbench

I'm having some trouble with importing .stf files in Translation Workbench: sometimes I get the following error in log file:

There were issues with import of file: t.stf
[No data to import.]

But the file clearly contains data. Furthermore, I can swear that it successfully imported the exact file in the past, but now it doesn't want to no matter how many times I try. I tried changing line endings but to no avail.
I found some solution in a Knowledge Article:

If you receive a "No Data to import" error and there is clearly data lines in your file, save the file with a new name and re-import the file.

But it doesn't work.

Best Answer

OK, I think I've got it. From the help page explaining what 'No data to import' message means:

The file you’re trying to import is empty or does not contain any translation changes.

It turned out that the file was actually imported earlier, so there were no changes detected in this import and it displayed this message.