conversion epub to pdf failed since 2.84

hello all

It's my first thread and it's about an issue I just encountered since I updated Calibre (Mac version) to the newest version 2.84.
For each epub file I tested to convert to PDF after few seconds I got an error and it looks it's always the same at the end of the details I have this

Processing /var/folders/d5/hn1yhp1j6mbdynz7hf_nysn80000gn/C/calibre_2.84.0_tmp_fBQz9q/XWby5E_pdf_out/OEBPS/ident1-2.html...
Processing /var/folders/d5/hn1yhp1j6mbdynz7hf_nysn80000gn/C/calibre_2.84.0_tmp_fBQz9q/XWby5E_pdf_out/OEBPS/pre2.html...
Loading font: family_name=Times New Roman full_name=Times New Roman Bold postscript_name=TimesNewRomanPS-BoldMT subfamily_name=Bold
Rendering failed
Traceback (most recent call last):
File "site-packages/calibre/ebooks/pdf/render/from_html.py", line 286, in render_html
File "site-packages/calibre/ebooks/pdf/render/from_html.py", line 416, in do_paged_render
File "site-packages/calibre/ebooks/pdf/render/engine.py", line 331, in add_links
TypeError: 'NoneType' object has no attribute '__getitem__'

Is it a bug or something else

please :help:

:thanks:

bkantique