Adam Warren 

Adam Warren said:

It would be wise to save the "outgoing " SDLXLIFF file before doing this.

What do you mean by "outgoing SDLXLIFF file" ?
The SDLXLIFF file is bilingual and basically contains all the translation work you did in a project, in this sense, it is both ingoing and outgoing.

If you save this file at the beginning of your work by hitting CTRL-S, which is best practice, you can always recover your project, whatever happens. 

In addition, Studio saves a copy of this file in the AutoSave folder every 10 minutes by default.

I'm sorry. I'm afraid I was rather telegraphic in my wording.

I mean that it's important to save the SDLXLIFF file previously generated - in single-file mode - from which I couldn't extract the target file, so that it won't be overwritten in project mode. 

You would then save time by re-using this first SDLXLIFF file in the project mode, if possible.

If that fails, of course, then a pre-translate yielding the newly-generated SDLXLIFF file, in project mode, would be necessary, but that would entail and end-to-end check of the resulting target file.

I hope that has made matters clearer.

With kind regards,

Adam.

Adam Warren said:

so that it won't be overwritten in project mode. 

The SDLXLIFF file will never be overwritten accidentally. If you start a new project, it will be located in a different folder than the one you created in single-file mode, even if the filename is the same.

Working with a complex file system. things can get mislaid, and did so. Respectfully, to save confusion, it would still be a good idea to save the original SDLXLIFF file in a safe directory, and then re-inject it in Project mode.

With kind regards,

Adam.