AttributeError: 'PngImageFile' object has no attribute '_PngImageFile__frame'

[parano]

What did you do?

My library BentoML is using imageio and Pillow in its tests, and with the latest release of Pillow 7.1.0 half an hour ago, I noticed some existing tests are breaking.

https://github.com/bentoml/BentoML
https://travis-ci.org/github/bentoml/BentoML/jobs/669765333?utm_medium=notification&utm_source=github_status

What did you expect to happen?

imageio.imread('./image.png') should work

What actually happened?

AttributeError: 'PngImageFile' object has no attribute '_PngImageFile__frame'

What are your OS, Python and Pillow versions?

• OS: mac os
• Python: 3.75
• Pillow: 7.1.0
• imageio: 2.8.0

from imageio import imread
imread('./test.png')

It seems related to #4243

[hugovk]

Git bisect says 67e3ccf is the first bad commit, from #4243.

commit 67e3ccffeb09903e22c29d737e74070415890ed8
Date:   Sun Dec 1 12:50:21 2019 +0900

    Add APNG support

    See #3483

    Adds support for reading APNG files and seeking through frames,
    and adds basic support for writing APNG files.

 src/PIL/PngImagePlugin.py | 401 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 390 insertions(+), 11 deletions(-)

@pmrowla Hi, please could you check this? Thank you!

[hugovk]

Ping @almarklein from https://github.com/imageio/imageio, FYI.

[hugovk]

Minimal test case, not using imageio:

from PIL import Image

im = Image.open("Tests/images/hopper.png")
im.seek(0)

Possible fix:

diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index 5bb0e2ff..afa39bc9 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -631,6 +631,7 @@ class PngImageFile(ImageFile.ImageFile):

     format = "PNG"
     format_description = "Portable network graphics"
+    __frame = 0

     def _open(self):

[tlambert03]

we're seeing this too in our tests at napari.

[hugovk]

Possible fix: #4512.

[pmrowla]

@hugovk's change in #4512 fixes this for me. Sorry for the hassle everyone!

[SteveDoyle2]

I'm seeing this too. I believe it's caused by PIL 7.1.0. 7.0.0 works fine.

[hugovk]

@pmrowla Thanks for checking! I've merged #4512.

Others: if you could test with master for any other regressions, that'd be appreciated.

[hugovk]

Pillow 7.1.1 has been released with a fix for this: #4354 (comment).

Thanks all!

[tlambert03]

Thanks for the very quick fix! just curious whether think you might end up removing 7.1.0 from pypi? (or whether we should keep Pillow!=7.1.0 in our requirements.txt even if pillow is just an indirect dependency)

[hugovk]

For an indirect dependency, you're probably fine removing it, especially as there was only a short time between 7.1.0 and 7.1.1.

If the problem comes up (seldom), you could ask people to upgrade. If it comes up a lot, you could pin it, or alternatively ask the dependency to add !=7.1.0.

[tlambert03]

can do. thanks!

[nabobalis]

Moved to #4518

[hugovk]

@nabobalis I'd guess this is also a Pillow bug, there were big changes to PngImagePlugin.py in 7.1. Please could you report a new issue? https://github.com/python-pillow/Pillow/issues/new?template=ISSUE_REPORT.md

@pmrowla Please could you have a look at this?

See also google/fonts#2380 (comment).

Thanks!

[hugovk]

We've merged a fix (#4528) for the new bug (#4518). Before we release, it would be helpful if people could run their test suites with the master branch to check if there are other regressions. Thanks!

[tlambert03]

I can confirm for napari that all tests fails and issues we observed in 7.1.0 and 7.1.1 are fixed in 7.2.0.dev0. thanks!

[radarhere]

Pillow 7.1.2 has now been released with the fix for the second problem described here.