Which biblatex/biber version produces BBL format 2.8?

If you are looking for help with biblatex and Biber for arXiv uploads, have a look at https://github.com/plk/biblatex/wiki/biblatex-and-the-arXiv and Biblatex and arxiv, error. This answer here mainly addresses the question in the title at face value.

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In general, the .bbl file version need not correspond to either the biblatex or the Biber version. The same goes for the .bcf version. The .bbl and .bcf versions can be stepped up with a biblatex/Biber release, but they need not be. In practice that means that the versions trail behind the biblatex/Biber versions and there is only an approximate correspondence between them and the actual package versions.

biblatex 3.5, 3.6 and 3.7 all need .bbl format version 2.8. The corresponding Biber versions are 2.6 (for biblatex 3.5 and 3.6) and 2.7 (for biblatex 3.7). biblatex 3.4 needs .bbl version 2.7, biblatex 3.8 has .bbl version 2.9.

So the newest combination that works with .bbl 2.8 is biblatex 3.7/Biber 2.7. As far as I know that is indeed the version arXiv is using after the February 2017 update Biblatex and arxiv, error.

You can find historic releases of biblatex and Biber at GitHub (https://github.com/plk/biblatex/releases, https://github.com/plk/biber/releases) and SourceForge (https://sourceforge.net/projects/biblatex/files/, https://sourceforge.net/projects/biblatex-biber/files/biblatex-biber/).

I managed to workaround the problem doing the following:

1. Upload the Latex project in overleaf.
2. Compile your project in Overleaf.
3. In the view window, go to the option "Other logs & Files" and download the ".bbl" file. At this time, when I checked the ".bbl" file of Overleaf, it is exactly the version 2.8 of Biblatex.
4. Rename the "output.bbl" (that you've go from compilation in Overleaf) to the same filename of the ".tex" file which you want to submit to Arxiv.
5. Upload ".tex", ".bbl" and other supporting files (figures and ".cls") to Arxiv.

It should work now, at least it has worked for me. Thus, this workaround can avoid local installing old versions of Latex and biblate in your computer.

My answer just put together what other people said in separate answers. It worked for me without the need to downgrade packages locally.

1. Upload the Latex project in overleaf (https://www.overleaf.com/).

2. Click on the Menu button on the top left. Select 2017 as the version for the Tex Live Version in the settings.

3. Compile your project in Overleaf.

4. In the view window, go to the option "Other logs & Files" and download the .bbl file. Rename the output .bbl (that you've go from compilation in Overleaf) to the same filename of the .tex file which you want to submit to Arxiv.

5. Upload the renamed .bbl file (and with the .tex file) to arXiv.