Windsurf
storage
Blob Storage Corrupting Uploaded Files in Windsurf App
Files uploaded to blob storage through your Windsurf-generated app become corrupted when downloaded. PDFs are unreadable, images show garbled data, ZIP files fail to extract, and documents open as random characters. The upload appears to succeed, but the stored file is damaged.
This is a particularly insidious bug because uploads appear successful — no errors are thrown, the file shows up in storage, and the file size may even look correct. But when a user downloads and opens the file, it's broken.
The corruption typically affects binary files (images, PDFs, ZIPs) while text files may work fine, which is a strong clue that the issue is related to encoding or stream handling.
Error Messages You Might See
Error: Invalid or corrupted PDF
Failed to decode image
Error: End-of-central-directory signature not found (ZIP)
The file is damaged and could not be opened
UTF-8 decode error on binary data
Common Causes
- UTF-8 encoding applied to binary data — Cascade read the file as a UTF-8 string instead of a Buffer, destroying binary data during encoding conversion
- Base64 double-encoding — The file is base64-encoded before upload, but the storage client also encodes it, resulting in double-encoded data
- Wrong content-type on upload — The file is uploaded with content-type: text/plain or application/json instead of its actual MIME type
- Stream not piped correctly — The readable stream is consumed (read to string) before being passed to the storage upload, instead of being piped directly
- Multipart boundary parsing error — The multipart form parser mishandles the file boundaries, truncating or appending extra bytes
How to Fix It
- Always use Buffer for binary files — Never call toString() on file data. Use Buffer objects or ArrayBuffer throughout the upload pipeline
- Set the correct content-type — Detect the MIME type using the file-type library or the upload's mimetype field, and pass it to the storage upload call
- Avoid double-encoding — Check if your storage client already handles encoding. Don't base64-encode if the client expects a Buffer or stream
- Pipe streams directly — Instead of reading the entire file into memory, pipe the upload stream directly to the storage write stream
- Verify with checksums — Generate an MD5 hash before upload and after download to confirm the file is identical. If hashes differ, the corruption is in the upload path
- Test with binary files specifically — Upload a small PNG or PDF and download it immediately. Open it to verify integrity before shipping to production
Real developers can help you.
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
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.
Matt Butler
Software Engineer @ AWS
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.
Pratik
SWE with 15+ years of experience building and maintaining web apps and extensive BE infrastructure
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.
prajwalfullstack
Hi Im a full stack developer, a vibe coded MVP to Market ready product, I'm here to help
Nam Tran
10 years as fullstack developer
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)
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.
You don't need to be technical. Just describe what's wrong and a verified developer will handle the rest.
Get HelpFrequently Asked Questions
Why do text files upload fine but images get corrupted?
Text files survive UTF-8 encoding because they're already text. Binary files (images, PDFs, ZIPs) contain byte sequences that are invalid UTF-8, so encoding them as strings destroys the data. Always handle binary files as Buffers.
How can I tell if corruption happens during upload or download?
Check the file directly in your storage dashboard (S3 console, Supabase dashboard). Download it from there. If it's corrupt in storage, the upload is the problem. If it's fine in storage but corrupt when downloaded through your app, the download handler is the issue.