I/O Errors (E4xxx)

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Code	Name	Description	Common Cause
`E4001`	FileNotFound	File not found	Source file path does not exist
`E4002`	PermissionDenied	Permission denied	Cannot read source file or write output
`E4003`	ImportNotFound	Import not found	Imported file not found in any include path
`E4004`	CircularImport	Circular import detected	File A imports B which imports A

Example: E4003 ImportNotFound

error[E4003]: import not found: '@neo/devpack/NeoToken.sol'
  --> MyContract.sol:3:1
   |
 3 | import "@neo/devpack/NeoToken.sol";
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Fix: Add the correct include path:

bash

neo-solc contract.sol -I devpack -I ./node_modules -o build/

Checklist:

Verify the import path matches the actual file location
Check that -I paths are relative to the working directory or absolute
Ensure no typos in the import statement
For devpack imports, ensure the devpack/ directory is present in the project

Example: E4004 CircularImport

error[E4004]: circular import detected: A.sol -> B.sol -> A.sol

Fix: Break the circular dependency by extracting shared types into a third file that both can import, or restructure the contract hierarchy.