dotnet/efcore · error · OperationException

No files were generated in directory

Error message

No files were generated in directory '{outputDirectoryName}'. The following file(s) already exist(s) and must be made writeable to continue: {readOnlyFiles}.

What it means

Thrown by CompiledModelScaffolder when writing the generated compiled-model files and one or more target paths already exist with the read-only file attribute. The scaffolder refuses to overwrite read-only files, collects the offending paths, and throws OperationException (DesignStrings.ReadOnlyFiles) listing them so they can be made writable.

Solutions

Remove the read-only attribute from the listed files: chmod +w (Linux/mac) or attrib -R (Windows), or delete them.
Clear the output directory before regenerating.
Ensure the output directory is writable by the user running the tool.

Example fix

# before: files are read-only
chmod -R u+w OutputDir/
# or remove and regenerate
rm -rf OutputDir/ && dotnet ef dbcontext optimize

Defensive patterns

Strategy: validation

Validate before calling

// Ensure output files are writable before scaffolding
foreach (var f in Directory.GetFiles(outputDir, "*.cs", SearchOption.AllDirectories))
    if ((File.GetAttributes(f) & FileAttributes.ReadOnly) != 0)
        File.SetAttributes(f, File.GetAttributes(f) & ~FileAttributes.ReadOnly);

Try / catch

try { scaffolder.Save(outputDir); }
catch (OperationException ex) when (ex.Message.Contains("writeable"))
{ /* chmod/attrib the listed files, or delete the directory and retry */ }

Prevention

Write compiled-model output to a directory not under a read-only source-control attribute.
Clear or chmod the output directory before regenerating.
In CI, write to a fresh working directory.

When it happens

Trigger: Running 'dotnet ef dbcontext optimize' (or programmatic compiled-model scaffolding) into a directory where a previous generation produced files that are now read-only.

Common situations: Files checked into source control that applies a read-only attribute; output generated on one OS/filesystem and copied to another; CI that marks artifacts read-only; a previous --force run left read-only files.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/bfd7661dae5b5e88. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Design/Scaffolding/Internal/CompiledModelScaffolder.cs:90

        var savedFiles = new List<string>();
        foreach (var file in scaffoldedModel)
        {
            var fullPath = Path.Combine(outputDir, file.Path);

            if (File.Exists(fullPath)
                && File.GetAttributes(fullPath).HasFlag(FileAttributes.ReadOnly))
            {
                readOnlyFiles.Add(file.Path);
            }
            else
            {
                File.WriteAllText(fullPath, file.Code, new UTF8Encoding(encoderShouldEmitUTF8Identifier: false));
                savedFiles.Add(fullPath);
            }
        }

        return readOnlyFiles.Count != 0
            ? throw new OperationException(
                DesignStrings.ReadOnlyFiles(
                    outputDir,
                    string.Join(CultureInfo.CurrentCulture.TextInfo.ListSeparator, readOnlyFiles)))
            : (IReadOnlyList<string>)savedFiles;
    }
}

View on GitHub (pinned to 3a2006ef56)