Sphinx 2.4.1 - Unable to use rst2pdf

[Culip]

Describe the bug
I regularly have exported PDF using rst2pdf in the past few months. I upgraded Sphinx from 2.3 to 2.4.1. Since then, the following command no longer works:

sphinx-build -b pdf /home/sarah/sphinxProject/source/ /home/sarah/sphinxProject/build/

Expected behavior. A PDF file shall be created under the build directory.

Actual behavior. I get the following error instead:

Traceback (most recent call last):
  File "/home/sarah/sphinxProject/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 216, in assemble_doctree
    self.env.indexentries={docname:self.env.indexentries[docname+'-gen']}
KeyError: 'index-gen'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/sarah/sphinxProject/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 141, in write
    appendices=opts.get('pdf_appendices', self.config.pdf_appendices) or [])
  File "/home/sarah/sphinxProject/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 218, in assemble_doctree
    self.env.indexentries={}
AttributeError: can't set attribute
FAILED
build succeeded.

I created a new Sphinx 2.4.1 environment and I was able to reproduce the same issue.

To Reproduce

$ mkdir sphinxTest
$ cd    sphinxTest
$ python3 -m pip install --user virtualenv
$ pip install --user --upgrade pip
$ python3 -m venv env
$ source ./env/bin/activate
(env) pip install --upgrade pip
(env) pip install -U sphinx
(env) sphinx-quickstart
(env) make html     # Confirmed the HTML version was created with no issues.
(env) pip install rst2pdf
(env) vi ./source/conf.py

Add the lines in {{./source/conf.py}}

extensions = ['rst2pdf.pdfbuilder']

pdf_documents = [(
    'index',
    u'testRst2Pdf',
    u'Test Title',
    u'Sarah Author')]

Save it and go back to the shell.

(env) sphinx-build -b pdf ./source/ ./build/
Running Sphinx v2.4.1
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [pdf]: targets for 1 source files that are out of date
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
processing testRst2Pdf...
index
[ERROR] pdfbuilder.py:149 can't set attribute
Traceback (most recent call last):
  File "/home/sarah/sphinxTest/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 216, in assemble_doctree
    self.env.indexentries={docname:self.env.indexentries[docname+'-gen']}
KeyError: 'index-gen'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/sarah/sphinxTest/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 141, in write
    appendices=opts.get('pdf_appendices', self.config.pdf_appendices) or [])
  File "/home/sarah/sphinxTest/env/lib64/python3.6/site-packages/rst2pdf/pdfbuilder.py", line 218, in assemble_doctree
    self.env.indexentries={}
AttributeError: can't set attribute
FAILED
build succeeded.
(env)

Expected behavior
A PDF file should be created under the output target (build).

Your project
N/A

Screenshots
N/A

Environment info

• OS: Linux centos 3.10.0-1062.12.1 x86_64
• Python version: 3.6.8
• Sphinx version: 2.4.1
• Sphinx extensions: ['rst2pdf.pdfbuilder']
• Extra tools: N/A

Additional context
N/A

[tk0miya]

Fixed by #7158
Thank you for reporting.