I am seeing this error on Heroku in a ruby on rails 6.0.2 app.
JSON::ParserError: 767: unexpected token at '' (Most recent call first)
which is occuring at line 9 of app/bin/rake.
4 rescue LoadError => e
5 raise unless e.message.include?('spring')
6 end
7 require_relative '../config/boot'
8 require 'rake'
9 Rake.application.run
The traceback shows it is happening in the active_storage video_analyzer.rb file:
/app/vendor/ruby-2.6.5/lib/ruby/2.6.0/json/common.rb line 156 in parse
File /app/vendor/ruby-2.6.5/lib/ruby/2.6.0/json/common.rb line 156 in parse
File /app/vendor/bundle/ruby/2.6.0/gems/activestorage-6.0.2/lib/active_storage/analyzer/video_analyzer.rb line 107 in block in probe_from
And the video_analyzer is being called ultimately by delayed_job. The app is uploading videos, but I am seeing no problems in either the upload or viewing of the videos. So what is causing this exception? I only started seeing the problem after upgrading from rails 5 to rails 6.
Although I had included the ffmpeg gem, on heroku I still needed to install the ffmpeg binaries on heroku. I tried this buildpack with the following commands:
heroku buildpacks:add --index 1 https://github.com/laddhadhiraj/heroku-buildpack-ffmpeg
heroku config:set FFMPEG_BIN_URL="http://johnvansickle.com/ffmpeg/releases/ffmpeg-release-64bit-static.tar.xz"
However, the FFMPEG_BIN_URL was out of date. Nevertheless, the buildpack installs ffmpeg and ffprobe. It can be seen from the error message, that the problem is caused by the lack of ffprobe, so this seems to have fixed the error message. It not clear that activestorage functionality is working completely with ffmpeg as the following methods have not been installed, ffserver, ffmpeg-10bit, qt-faststart
If anyone knows of a more up-to-date buildpack, please post an answer or comment.