Claude Code storage

File Write Operations Failing with Permission Errors

Your application fails when trying to write files to disk, throwing EACCES, EPERM, or permission denied errors. File uploads, log writing, cache storage, or report generation all fail because the application process doesn't have write access to the target directories.

This commonly happens when Claude Code generates code that writes to absolute paths like /tmp, /var, or the project root directory, but the deployment environment (Docker container, cloud function, or restricted server) doesn't allow writes to those locations.

The code works perfectly in local development where you run as an admin user, but breaks immediately in production where the application runs as a restricted service account.

Error Messages You Might See

Error: EACCES: permission denied, open '/var/data/output.pdf' EPERM: operation not permitted, mkdir '/app/uploads' OSError: [Errno 13] Permission denied: '/opt/data/cache' Read-only file system
Error: EACCES: permission denied, open '/var/data/output.pdf'EPERM: operation not permitted, mkdir '/app/uploads'OSError: [Errno 13] Permission denied: '/opt/data/cache'Read-only file system

Common Causes

  • Hardcoded absolute paths — Code writes to /tmp or /var/data which may be read-only in containerized environments
  • Read-only filesystem in serverless — Cloud functions and some container runtimes have read-only root filesystems
  • Docker container running as non-root — The application user inside the container doesn't own the target directory
  • Missing directory creation — Code tries to write a file before creating its parent directory
  • SELinux or AppArmor restrictions — Security modules blocking file writes even when Unix permissions allow them

How to Fix It

  1. Use os.tmpdir() or platform-agnostic paths — Replace hardcoded paths with Node's os.tmpdir() or Python's tempfile.gettempdir()
  2. Create directories before writing — Always call fs.mkdirSync(dir, {recursive: true}) or os.makedirs(dir, exist_ok=True) before file operations
  3. Use /tmp in serverless — In AWS Lambda or similar, /tmp is the only writable directory. Configure your app to use it
  4. Set correct Docker permissions — Add RUN chown -R appuser:appuser /app/data in your Dockerfile for writable directories
  5. Use object storage for production — Replace local file writes with S3, GCS, or Supabase Storage for production deployments

Real developers can help you.

Luca Liberati Luca Liberati I work on monoliths and microservices, backends and frontends, manage K8s clusters and love to design apps architecture MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. zipking zipking I am a technologist and product builder dedicated to creating high-impact solutions at the intersection of AI and specialized markets. Currently, I am focused on PropScan (EstateGuard), an AI-driven SaaS platform tailored for the Japanese real estate industry, and exploring the potential of Archify. As an INFJ-T, I approach development with a "systems-thinking" mindset—balancing technical precision with a deep understanding of user needs. I particularly enjoy the challenge of architecting Vertical AI SaaS and optimizing Small Language Models (SLMs) to solve specific, real-world business problems. Whether I'm in a CTO-level leadership role or hands-on with the code, I thrive on building tools that turn complex data into actionable value. hanson1014 hanson1014 Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround. Vlad Temian Vlad Temian 15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox). Cursor ambassador and agentic tooling builder. I've scaled systems, automated deployments, and built observability tools for AI coding workflows. I specialize in taking vibe-coded apps from broken prototype to production-ready: fixing Supabase auth/RLS, Stripe integrations, deployment pipelines, and cleaning up AI-generated spaghetti. I build tools in this space (agentprobe, claudebin, micode) and understand both sides: how AI generates code and why it breaks. https://blog.vtemian.com/ Jared Hasson Jared Hasson Full time lead founding dev at a cyber security saas startup, with 10 yoe and a bachelor's in CS. Building & debugging software products is what I've spent my time on for forever Jen Jacobsen Jen Jacobsen I’m a Full-Stack Developer with over 10 years of experience building modern web and mobile applications. I enjoy working across the full product lifecycle — turning ideas into real, well-built products that are intuitive for users and scalable for businesses. I particularly enjoy building mobile apps, modern web platforms, and solving complex technical problems in a way that keeps systems clean, reliable, and easy to maintain. Caio Rodrigues Caio Rodrigues I'm a full-stack developer focused on building practical and scalable web applications. My main experience is with **React, TypeScript, and modern frontend architectures**, where I prioritize clean code, component reusability, and maintainable project structures. I have strong experience working with **dynamic forms, state management (Redux / React Hook Form), and complex data-driven interfaces**. I enjoy solving real-world problems by turning ideas into reliable software that companies can actually use in their daily operations. Beyond coding, I care about **software quality and architecture**, following best practices for componentization, code organization, and performance optimization. I'm also comfortable working across the stack when needed, integrating APIs, handling business logic, and helping transform prototypes into production-ready systems. My goal is always to deliver solutions that are **simple, efficient, and genuinely useful for the people using them.** Alvin Voo Alvin Voo I’ve watched the tech landscape evolve over the last decade—from the structured days of Java Server Pages to the current "wild west" of Agentic-driven development. While AI can "vibe" a frontend into existence, I specialize in the architecture that keeps it from collapsing. My expertise lies in the critical backend infrastructure: the parts that must be fast, secure, and scalable. I thrive on high-pressure environments, such as when I had only three weeks to architect and launch an Ethereum redemption system with minimal prior crypto knowledge, turning it into a major revenue stream. What I bring to your project: Forensic Debugging: I don't just "patch" bugs; I use tools like Datadog and Explain Analyzers to map out bottlenecks and resolve root causes—like significantly reducing memory usage by optimizing complex DB joins. Full-Stack Context: Deep experience in Node.js and React, ensuring backends play perfectly with mobile and web teams. Sanity in the Age of AI: I bridge the gap between "best practices" and modern speed, ensuring your project isn't just built fast, but built to last. Jacek Rozanski Jacek Rozanski Senior PHP/Symfony developer and DevOps engineer with 20+ years of professional experience, running opcode.pl (web development agency, est. 2004). Day job: I'm the sole backend developer at merketing company where I own and maintain 11 PHP/Symfony microservices on AWS (ECS Fargate, RDS, S3, CloudFront), handle the full CI/CD pipeline (Bitbucket Pipelines, Docker), and manage monitoring with Sentry and CloudWatch. These services handle high request volumes in production every month. What I bring to AI-built apps: - I audit and fix security issues (OWASP methodology), performance bottlenecks, and architectural problems in codebases generated by Cursor, Claude Code, Lovable, Bolt, and v0 - I refactor AI-generated prototypes into production-grade applications with proper error handling, testing, and clean architecture (SOLID, DDD, hexagonal architecture) - I set up the infrastructure AI tools don't touch: AWS hosting, CI/CD pipelines, automated deployments, database optimization, monitoring, and alerting - I integrate external services: payment providers, email systems, partner APIs, SSO/auth Tech stack: PHP 8.x, Symfony, React, Next.js, PostgreSQL, MySQL, Docker, AWS (ECS, RDS, S3, SQS/SNS, CloudFront), Terraform, Supabase. I also use AI tools daily (Claude Code, Cursor) in my own workflow, so I understand both the strengths and the gaps in AI-generated code. Based in Poland (CET timezone). Available for async work and calls during EU/US business hours.

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Frequently Asked Questions

Why does file writing work locally but not in production?

Local development typically runs as your user with full permissions. Production environments (Docker, serverless, cloud VMs) run as restricted users with limited filesystem access. Always use platform-appropriate writable directories.

Where can I write files in AWS Lambda?

Only the /tmp directory is writable in Lambda, with a 512MB limit (configurable up to 10GB). For persistent storage, upload to S3 instead of writing locally.

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