Weasyprint: GLib-GObject-CRITICAL **: 21:14:11.559: g_object_ref: assertion 'old_val > 0' failed Segmentation fault: 11
I am trying to generate a PDF using WeasyPrint and jinja2. A basic flow of my code is below:
from jinja2 import Environment, FileSystemLoader
from weasyprint import HTML
jinja_env = Environment(loader=FileSystemLoader(template_path))
template = jinja_env.get_template(template_name)
html_out = template.render(template_vars)
HTML(string=html_out, base_url='imgs/').write_pdf(target=out_path,stylesheets=['style.css'])
(process:5306): GLib-GObject-CRITICAL **: 21:14:11.559: g_object_ref: assertion 'old_val > 0' failed
Segmentation fault: 11
I am happy to provide anything that would help reporduce the issue (apologies I am new to using WeasyPrint and jinja2). I've never seen an error like this before.
I have seen similar issues #829 but is there any course of action to investigate what is causing the issue if it's not WeasyPrint?
loganthomas
All 14 comments
Hello!
I am happy to provide anything that would help reporduce the issue (apologies I am new to using WeasyPrint and jinja2). I've never seen an error like this before.
Using jinja here is not related to your problem. template.render() generates a string that is read by WeasyPrint later. Using a normal string should give the same problem.
If you want to help, you can provide an sample that like this that raises your error:
from weasyprint import HTML
html = """
<html>
…
</html>
"""
HTML(string=html).write_pdf(target='/tmp/test.pdf')
Then give the whole traceback you get.
If you can't reproduce your error with a simple script, then you can provide more information about your OS, your application and the libraries installed on your system.
Also, if your code used to work but doesn't anymore, you can try to find what has changed on your system.
If you get this error also on macOS (like for #829), then there's probably been an update of glib that breaks things.
I have seen similar issues #829 but is there any course of action to investigate what is causing the issue if it's not WeasyPrint?
When there's a crash, you can look a the stack trace, it will probably help you to find where the error comes from.
liZe
on 21 Mar 2019
Thanks so much!
A brief recap of my investigation:
1. Simple test
from weasyprint import HTML
```html
html = """
<div style="text-align:center">
<h1>PDF Title Page</h1>
<h2><i>Subtitle</i></h2>
</div>
<p style="page-break-before: always"></p>
<h1>Page #2</h1>
"""
```python
HTML(string=html).write_pdf(target='/tmp/test.pdf')
The PDF gets written as expected, but I get the below error that kicks me out of my python session. If I was just writing one PDF, I could deal with it. But, I am writing multiple PDFs in a loop and this error message is problamtic (as it will only write the first PDF in my loop then exit).
#Output
(process:697): GLib-GObject-CRITICAL **: 07:19:50.623: g_object_ref: assertion 'old_val > 0' failed
Bus error: 10
2. Look at stack trace
This wasn't helpful. Maybe I have an un-trained eye, but I couldn't see anything that would point me in the direction of the error. I have the logs is you'd like to see them.
3. glib?
I am, in fact, running on MacOS. I looked at glib in my Homebrew downloads (/usr/local/Cellar) and the version of glib showed 2.60.0_1.
Uninstalled glib.
brew uninstall --ignore-dependencies --force glib
Tried to run my program (knowing it would fail since I uninstalled glib). Got this error.
Traceback (most recent call last):
File "run_perf_analysis.py", line 19, in <module>
from make_pdf_report import report_funcs as rf
File "/make_pdf_report/report_funcs.py", line 13, in <module>
from weasyprint import HTML
File "/anaconda3/lib/python3.7/site-packages/weasyprint/__init__.py", line 393, in <module>
from .css import preprocess_stylesheet # noqa
File "/anaconda3/lib/python3.7/site-packages/weasyprint/css/__init__.py", line 26, in <module>
from . import computed_values
File "/anaconda3/lib/python3.7/site-packages/weasyprint/css/computed_values.py", line 17, in <module>
from .. import text
File "/anaconda3/lib/python3.7/site-packages/weasyprint/text.py", line 249, in <module>
'libpango-1.0.dylib')
File "/anaconda3/lib/python3.7/site-packages/weasyprint/text.py", line 243, in dlopen
return ffi.dlopen(names[0]) # pragma: no cover
File "/anaconda3/lib/python3.7/site-packages/cffi/api.py", line 141, in dlopen
lib, function_cache = _make_ffi_library(self, name, flags)
File "/anaconda3/lib/python3.7/site-packages/cffi/api.py", line 802, in _make_ffi_library
backendlib = _load_backend_lib(backend, libname, flags)
File "/anaconda3/lib/python3.7/site-packages/cffi/api.py", line 798, in _load_backend_lib
return backend.load_library(path, flags)
OSError: cannot load library '/usr/local/lib/libpango-1.0.dylib': dlopen(/usr/local/lib/libpango-1.0.dylib, 2): Library not loaded: /usr/local/opt/glib/lib/libgobject-2.0.0.dylib
Referenced from: /usr/local/lib/libpango-1.0.dylib
Reason: image not found
Re-installed glib
brew install glib
Still get the same initial error code:
(process:8135): GLib-GObject-CRITICAL **: 08:02:35.016: g_object_ref: assertion 'old_val > 0' failed
Bus error: 10
I think this may be a glib version issue like you mentioned, but how would I go about fixing this?
loganthomas
on 21 Mar 2019
I am, in fact, running on MacOS.
Then you can be pretty sure that there's something wrong with glib-2.60.0 provided by homebrew. The same error on macOS reported twice the week glib is updated is not a coincidence. Is there a way to install an older version?
I have the logs is you'd like to see them.
Yes, and you can also post the trace corresponding to your script. Does the script fail if you just add a for-loop like:
for i in range(5):
HTML(string=html).write_pdf(target=f'/tmp/test-{i}.pdf')
Only test-0.pdf gets written
loganthomas
on 21 Mar 2019
Only test-0.pdf gets written
Well, it's a good old segmentation fault, and you'll need a debugger to find what's going on (I don't even know if it's possible with Python using CFFI). Unfortunately, I can't reproduce on Linux. TravisCI's build is OK too, even with glib-2.60.0.
Maybe you'll learn something by calling dmesg in a terminal.
Opening an issue on glib's GitLab and/or homebrew's GitHub may be useful to have more information about what's going on and how to fix it.
liZe
on 21 Mar 2019
Thanks so much. Really appreciate your help here. I have opened an issue in both places. I will update the thread if I hear anything or find a solution. Thank you again!
loganthomas
on 21 Mar 2019
Success! The homebrew team helped me out!
Homebrew shipped with python 3.7.2 and I had python 3.7.0.
I created a virtual env with python 3.7.2 and everything worked!
@hybridpicker for awareness
loganthomas
on 21 Mar 2019
I created a virtual env with python 3.7.2 and everything worked!
Good to know, thanks for taking the time to create issues and to give the solution here.
liZe
on 21 Mar 2019
Thanks for investigating!
For me I also needed to upgrade all my brew dependencies to solve this problem:
brew update && brew upgrade
timvink
on 31 Oct 2019
Success! The homebrew team helped me out!
Homebrew shipped with python 3.7.2 and I had python 3.7.0.
I created a virtual env with python 3.7.2 and everything worked!
@hybridpicker for awareness
Thank you for bothering to post the solution that fixed your problem. I have tried it and it worked perfectly for a different type of issue:
(process:12404): GLib-GObject-CRITICAL **: 23:41:11.459: g_object_ref: assertion '!object_already_finalized' failed
Bus error: 10
SimasJan
on 17 Nov 2020
I'm getting a similar error, however I get an error when I close out my Python session, or when I try to write the second iteration (first one writes fine).
I've tried the brew update && brew upgrade approach...
(process:21963): GLib-GObject-CRITICAL **: 17:37:52.617: g_object_ref: assertion '!object_already_finalized' failed
Homebrew ships with python 3.9.1, and I used Conda to create a virtual environment for 3.9.1 (normally using python 3.7.3). I still get the crashes.
jondoesntgit
on 20 Jan 2021
@jondoesntgit I ran into the same problem. I was able to work around it by following the macOS installation instructions, but jumping back to the general installation instructions at the top of that page. Those specify creating a clean virtual environment (a step missing from the macOS specific instructions) before actually running pip install WeasyPrint. Might be something worth looking at changing in the docs, since the instructions for both macOS and Windows don't mention the virtualenv step when walking the user through the remainder of installation.
mitchnegus
on 22 Jan 2021
Might be something worth looking at changing in the docs, since the instructions for both macOS and Windows don't mention the virtualenv step when walking the user through the remainder of installation.
You’re right. We will soon rewrite the documentation, we’ll put these steps for all the OSes.
liZe
on 22 Jan 2021
I finally got it to work by running
source activate py39
pip uninstall weasyprint
pip install weasyprint
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Most helpful comment
Success! The homebrew team helped me out!
Homebrew shipped with python 3.7.2 and I had python 3.7.0.
I created a virtual env with python 3.7.2 and everything worked!
@hybridpicker for awareness