Asked 1 month ago by NeptunianExplorer027
Asset Precompilation Fails on Heroku Due to SassC rgba Argument Error
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I'm encountering an asset precompilation error when deploying my Ruby on Rails app to Heroku.
During the push, I get the following error trace:
RUBYruby/concurrent/executor/ruby_thread_pool_executor.rb:341:in block (2 levels) in create_worker /tmp/build_f0149c13/vendor/bundle/ruby/3.1.0/gems/concurrent-ruby-1.3.4/lib/concurrent-ruby/concurrent/executor/ruby_thread_pool_executor.rb:340:in catch /tmp/build_f0149c13/vendor/bundle/ruby/3.1.0/gems/concurrent-ruby-1.3.4/lib/concurrent-ruby/concurrent/executor/ruby_thread_pool_executor.rb:340:in block in create_worker Tasks: TOP => assets:precompile (See full trace by running task with --trace)
and then:
BASH! Precompiling assets failed. ! ! Push rejected, failed to compile Ruby app. ! Push failed
Additional log details include:
BASH-----> Installing node-v22.11.0-linux-x64 -----> Detecting rake tasks -----> Preparing app for Rails asset pipeline Running: rake assets:precompile rake aborted! SassC::SyntaxError: Error: overloaded function rgba given wrong number of arguments on line 1:11446 of stdin >> -resize-helper{background:#555;background:rgba(0 0 0%);border:1px;border-rad ------------------------------------------^ stdin:1
The error indicates an issue with the SassC gem misinterpreting a call to the rgba function (likely expecting four parameters instead of the three provided).
I haven’t been able to locate any explicit rgba references in my own assets—my suspicion is that this code is coming from a gem or external asset. I've attempted the following troubleshooting steps:
- Running
rake assets:precompilelocally - Resetting assets
- Setting
config.assets.initialize_on_precompile = false - Checking for gem updates
Despite these attempts, the problematic code snippet appears as part of the error log:
BASH-resize-helper{background:#555;background:rgba(0 0 0%);border:1px;border-rad
Any insights on how to resolve this SassC-related precompilation error would be greatly appreciated.
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2 Answers
Answer by 
TychoAI Agent • 1 month ago
0
Based on the error message, SassC is reporting that an overloaded function call for rgba is receiving the wrong number of arguments (i.e. it’s being used with a syntax like "rgba(0 0 0%)" where SassC expects something like rgba(0, 0, 0, α)). Although you couldn’t locate this code in your own assets, it’s likely coming from a gem-provided stylesheet or asset that isn’t fully compatible with the version of SassC (or its underlying libsass implementation) that you’re using.
Here are some steps you can take to resolve the issue:
1. Check Gem Versions
-
SassC/SassC-Rails: Verify whether there is an update or known issue with the current version of sassc-rails or sassc gems. Sometimes, upgrading or downgrading these gems helps resolve syntax issues in SCSS files from dependencies.
-
Dependent Gems: If you suspect a gem (like a UI framework or a third-party stylesheet) might be providing the faulty syntax, check if there is an update or a patch for that gem.
2. Precompile Assets Locally
Since the Rails guides suggest that precompiling assets locally can help troubleshoot production-time issues, try running this command on your development machine:
BASHRAILS_ENV=production bin/rails assets:precompile
If the error is reproduced locally, you can inspect the compiled output (or the point at which it fails) to narrow down the source.
3. Use a Localized Asset Pipeline Configuration
If you need to bypass issues on the server, consider precompiling assets locally and then pushing them to Heroku. The Rails guides advise that in some deployment scenarios you should disable the asset precompile task on the server. For example, if you’re using deploy tools like Capistrano or manually handling assets, make sure:
- The asset precompile task isn’t redundantly run in production.
- Your compressors or minifiers are correctly set up on your development system.
4. Workaround or Patch
If you identify the particular stylesheet (even if it’s from a gem), you may be able to override it in your application’s assets by copying the file to your asset folder and correcting the syntax. This can help until an official fix or update is provided.
Recap
- Error: SassC::SyntaxError due to a wrong number of arguments in
rgba - Likely Cause: A gem’s stylesheet using incompatible SCSS syntax
- Solutions:
- Check for gem updates for SassC and any dependent gems.
- Precompile assets locally to isolate the issue.
- Consider setting up local asset precompilation and disabling it on Heroku if that fits your deployment workflow.
Following these steps should help you pinpoint and resolve the issue. Let me know if you need further details on any of these points.
Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?
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Answer by JovianCosmonaut283 • 1 month ago
0
It looks like you're missing a value in your rgba function. rgba stands for Red, Green, Blue, Alpha, where the Red, Green, and Blue values are expressed as integers from 0-255 and the Alpha is a percentage from 0-100% (or 0 to 1.0).
You wrote rgba(0, 0, 0%) — that's 0 for Red, 0 for Green, (missing) for Blue, and 0% (plain 0 would be fine here too) for Alpha.
Update it to rgba(0, 0, 0, 0%) and you should fix the error!
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