Hi Deimi, really thanks for the tests, they are needed and I never managed to create them.

I am closing this issue again.

Hi Deimi, I saw that you recently added more tests to https://github.com/dgalcius/t-tex4ht. That's really nice, thanks.

I finally fixed this issue yesterday. I've found that the issue with the Datetime package was that it loads the Ifthen package. Nameref then redefines the \ifthenelse command, which broke BibLaTeX in the sample file for this issue.

I had to put fixes to hyperref-hooks.4ht, to load Ifthen package explicitly before Nameref. We then revert \ifthenelse back to it's original definition in ifthen.4ht, before we apply TeX4ht hooks. With this, the redefinitions to \ifthenelse done by Nameref are lost. It were local redefinitions to \ref and \pageref commands. TeX4ht does some fixes to these commands in \ifthenelse too, so I guess that it should be OK to ignore Namerefs fixes.

I've introduced Nameref back into hyperref-hooks.4ht, because it caused issues for other users:

https://tex.stackexchange.com/q/623902/2891

It also broke new TeX4ht documentation, where I use the Nameref package.

So now BibLaTeX + Hyperref fails again.

Yes, this fixes it. Thanks!

I've found that the real problem was loading of Nameref in hyperref-hooks.4ht file. I've found that when I remove it, it fixes this issue, but also several other issues that were recently reported. I don't even know why it was there, I think this code was quite old. Anyway, I haven't found any errors when I removed it, so I hope we don't find any in the future.

The updated biblatex-hooks.4ht and hyperref-hooks.4ht files are attached.

(file #443, file #444)

This is following https://tex.stackexchange.com/a/619816/19291

As of rev. 1005, documents with biblatex that also load datetime fail due to the automatic loading of nameref.

If you compile the attached MW with

make4ht -f odt biblatex-fail
biber biblatex-fail
make4ht -f odt biblatex-fail

you'll get on the second make4ht run:

[ERROR] htlatex: Compilation errors in the htlatex run
[ERROR] htlatex: Filename Line Message
[ERROR] htlatex: ./biblatex-fail.tex 10 Argument of \@secondoftwo has an extra }.
[ERROR] htlatex: ./biblatex-fail.tex 10 Paragraph ended before \@secondoftwo was complete.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing = inserted for \ifnum.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.
[ERROR] htlatex: Compilation errors in the htlatex run
[ERROR] htlatex: Filename Line Message
[ERROR] htlatex: ./biblatex-fail.tex 10 Argument of \@secondoftwo has an extra }.
[ERROR] htlatex: ./biblatex-fail.tex 10 Paragraph ended before \@secondoftwo was complete.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing = inserted for \ifnum.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.
[ERROR] htlatex: Compilation errors in the htlatex run
[ERROR] htlatex: Filename Line Message
[ERROR] htlatex: ./biblatex-fail.tex 10 Argument of \@secondoftwo has an extra }.
[ERROR] htlatex: ./biblatex-fail.tex 10 Paragraph ended before \@secondoftwo was complete.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing = inserted for \ifnum.
[ERROR] htlatex: ./biblatex-fail.tex 10 Missing number, treated as zero.

If you remove the call to datetime, compilation succeeds.