Bolt
storage
File Upload Broken After Deploying Bolt App to Production
File uploads in your Bolt.new application work perfectly during development in the WebContainer but fail completely after deploying to production. Users see upload spinners that never finish, error messages about failed requests, or files that appear to upload but are never saved.
This is one of the most common deployment issues with Bolt apps because the WebContainer environment handles file storage differently than production hosting. Files stored locally during development have no persistent storage on serverless platforms like Vercel or Netlify.
The issue can manifest in several ways: uploads timeout with 413 or 504 errors, files are saved but disappear after deployment redeploys, or the upload endpoint returns CORS errors that didn't exist in development.
Error Messages You Might See
413 Request Entity Too Large
Error: ENOENT: no such file or directory, open '/tmp/uploads/...'
504 Gateway Timeout during file upload
StorageApiError: new row violates row-level security policy
TypeError: Failed to fetch (upload request)
Common Causes
- Local file system storage in serverless — Bolt generated code that saves files to the local filesystem (fs.writeFile), which is ephemeral on serverless platforms
- Missing cloud storage configuration — No Supabase Storage, AWS S3, or Cloudinary configuration for production file hosting
- File size limits on hosting platform — Vercel limits request body to 4.5MB, Netlify to 1MB by default, causing large uploads to silently fail
- CORS not configured on storage bucket — The cloud storage bucket doesn't allow uploads from your production domain
- Missing multipart form parsing — The API route doesn't parse multipart/form-data correctly in the production runtime
How to Fix It
- Switch to cloud storage — Replace local filesystem storage with Supabase Storage: const { data, error } = await supabase.storage.from('uploads').upload(filePath, file)
- Configure upload size limits — For Vercel, add to vercel.json: { "functions": { "api/**": { "maxDuration": 60 } } } and use streaming uploads for large files
- Set up CORS on storage bucket — In Supabase dashboard, configure the storage bucket to allow your production domain origin
- Use presigned URLs for large files — Generate a presigned upload URL on the server and upload directly from the browser to storage, bypassing your API
- Add proper error handling — Wrap upload logic in try-catch and return meaningful error messages instead of generic 500 errors
Real developers can help you.
Matthew Jordan
I've been working at a large software company named Kainos for 2 years, and mainly specialise in Platform Engineering. I regularly enjoy working on software products outside of work, and I'm a huge fan of game development using Unity. I personally enjoy Python & C# in my spare time, but I also specialise in multiple different platform-related technologies from my day job.
Taufan
I’m a product-focused engineer and tech leader who builds scalable systems and turns ideas into production-ready platforms.
Over the past years, I’ve worked across startups and fast-moving teams, leading backend architecture, improving system reliability, and shipping products used by thousands of users. My strength is not just writing code — but connecting product vision, technical execution, and business impact.
Sage Fulcher
Hey I'm Sage! Im a Boston area software engineer who grew up in South Florida. Ive worked at a ton of cool places like a telehealth kidney care startup that took part in a billion dollar merger (Cricket health/Interwell health), a boutique design agency where I got to work on a ton of exciting startups including a photography education app, a collegiate Esports league and more (Philosophie), a data analytics as a service startup in Cambridge (MA) as well as at Phillips and MIT Lincoln Lab where I designed and developed novel network security visualizations and analytics. I've been writing code and furiously devoted to using computers to make people’s lives easier for about 17 years. My degree is in making computers make pretty lights and sounds. Outside of work I love hip hop, the Celtics, professional wrestling, magic the gathering, photography, drumming, and guitars (both making and playing them)
MFox
Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking.
Matthew Butler
Systems Development Engineer @ Amazon Web Services
Stanislav Prigodich
15+ years building iOS and web apps at startups and enterprise companies. I want to use that experience to help builders ship real products - when something breaks, I'm here to fix it.
Pratik
SWE with 15+ years of experience building and maintaining web apps and extensive BE infrastructure
Basel Issmail
’m a Senior Full-Stack Developer and Tech Lead with experience designing and building scalable web platforms. I work across the full development lifecycle, from translating business requirements into technical architecture to delivering reliable production systems.
My work focuses on modern web technologies, including TypeScript, Angular, Node.js, and cloud-based architectures. I enjoy solving complex technical problems and helping teams turn product ideas and prototypes into working platforms that can grow and scale.
In addition to development, I often collaborate closely with product managers, business analysts, designers, and QA teams to ensure that solutions align with both technical and business goals.
I enjoy working with startups and product teams where I can contribute both as a hands-on engineer and as a technical partner in designing and delivering impactful software.
Victor Denisov
Developer
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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Get HelpFrequently Asked Questions
Why do uploads work locally but not in production?
In Bolt's WebContainer, files are stored in the local filesystem which is always available. In production on serverless platforms (Vercel, Netlify), the filesystem is read-only or ephemeral. You need to use cloud storage like Supabase Storage or AWS S3.
What is the maximum file size I can upload on Vercel?
Vercel's serverless functions have a 4.5MB request body limit. For larger files, use presigned URLs to upload directly to your storage bucket from the browser, bypassing the serverless function entirely.