Vercel / Deployment

Vercel Deploy Module Not Found Due to Case-Sensitive Filesystem on Windows

Fix Next.js/Vercel deploy module not found errors caused by case sensitivity differences between local Windows/macOS filesystem and Vercel's Linux build environment Includes evidence for Vercel troubleshooting demand.

Source-backed Last updated June 2, 2026 3 sources Needs local verification

Category: Deployment
Error signature: Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment
Quick fix: Check the build output, project root, and deployment platform configuration before redeploying.
Updated: June 2, 2026
Verification status: Source-backed
Evidence: 3 public source URLs

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Vercel, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment is a Vercel failure pattern reported for developers trying to fix next.js/vercel deploy module not found errors caused by case sensitivity differences between local windows/macos filesystem and vercel's linux build environment. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Verified issue on GitHub Issue #69390 (vercel/next.js) and multiple Vercel Community threads (8178, 4352, 18432). Local builds succeed on Windows/macOS (case-insensitive FS) but fail on Vercel (Linux case-sensitive). Specific examples: @/components/forms/RegisterForm vs register.ts, siteSettings vs SiteSettings, clsx import path casing. Fix: ensure exact case-match in import statements. Also related: vercel CLI succeeds locally but cloud build still fails, npm install getting corrupted on Vercel servers causing cascading CannotFindModule errors. Category mapping: Vercel → Deployment (per category rules). Covered-errors lists 'Vercel module not found' but this specific case-sensitivity variant is not explicitly covered.

Common causes

Verified issue on GitHub Issue #69390 (vercel/next.js) and multiple Vercel Community threads (8178, 4352, 18432). Local builds succeed on Windows/macOS (case-insensitive FS) but fail on Vercel (Linux case-sensitive). Specific examples: @/components/forms/RegisterForm vs register.ts, siteSettings vs SiteSettings, clsx import path casing. Fix: ensure exact case-match in import statements. Also related: vercel CLI succeeds locally but cloud build still fails, npm install getting corrupted on Vercel servers causing cascading CannotFindModule errors. Category mapping: Vercel → Deployment (per category rules). Covered-errors lists 'Vercel module not found' but this specific case-sensitivity variant is not explicitly covered.

Quick fixes

Confirm the exact error signature matches Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment.
Check the Vercel account, local tool state, and provider configuration involved in the failing workflow.
Check the build output, project root, and deployment platform configuration before redeploying.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment exactly before applying the quick fix.
Compare the failing environment with Vercel versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment mean in Vercel?

Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment indicates the workflow described by "Vercel Deploy Module Not Found Due to Case-Sensitive Filesystem on Windows" failed in a Deployment context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment?

Check whether this cause matches your environment: Verified issue on GitHub Issue #69390 (vercel/next.js) and multiple Vercel Community threads (8178, 4352, 18432). Local builds succeed on Windows/macOS (case-insensitive FS) but fail on Vercel (Linux case-sensitive). Specific examples: @/components/forms/RegisterForm vs register.ts, siteSettings vs SiteSettings, clsx import path casing. Fix: ensure exact case-match in import statements. Also related: vercel CLI succeeds locally but cloud build still fails, npm install getting corrupted on Vercel servers causing cascading CannotFindModule errors. Category mapping: Vercel → Deployment (per category rules). Covered-errors lists 'Vercel module not found' but this specific case-sensitivity variant is not explicitly covered.

Is the Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment guidance source-backed?

The "Vercel Deploy Module Not Found Due to Case-Sensitive Filesystem on Windows" page is labeled source-backed. It has 3 public source URLs from github.com, community.vercel.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment?

For "Vercel Deploy Module Not Found Due to Case-Sensitive Filesystem on Windows", avoid applying "Check the build output, project root, and deployment platform configuration before redeploying." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging Module not found: Can't resolve '@/components/forms/RegisterForm' — Build successful locally but fails on Vercel deployment?

For "Vercel Deploy Module Not Found Due to Case-Sensitive Filesystem on Windows", collect the failing Vercel command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.