DevToys-app/DevToys · error · FileNotFoundException

Unable to find the indicated file.

Error message

Unable to find the indicated file.

What it means

Thrown by DevToys.Windows FileStorage.OpenReadFile after resolving a relative path against AppCacheDirectory and finding the file absent via File.Exists. It is the Windows platform's implementation of the shared IFileStorage.OpenReadFile contract. FileNotFoundException carries the resolved path.

Solutions

  1. Call IFileStorage.FileExists(path) immediately before OpenReadFile and handle the false case.
  2. Inspect the resolved path (AppCacheDirectory + relative) to confirm it is the expected location.
  3. Ensure the producer (OpenWriteFile) completed before the consumer reads.
  4. For packaged/MSIX apps, confirm the path is inside the permitted app data folder.
  5. Catch FileNotFoundException and recover (recreate, reprompt, skip).

Example fix

// before
using FileStream stream = fileStorage.OpenReadFile(relativePath);

// after
if (!fileStorage.FileExists(relativePath))
{
    return; // or recreate / reprompt
}
using FileStream stream = fileStorage.OpenReadFile(relativePath);
Defensive patterns

Strategy: validation

Validate before calling

string resolved = Path.IsPathRooted(path) ? path : Path.Combine(fileStorage.AppCacheDirectory, path);
if (!File.Exists(resolved))
{
    return; // or recreate / reprompt
}
using FileStream stream = fileStorage.OpenReadFile(path);

Try / catch

try
{
    using FileStream stream = fileStorage.OpenReadFile(path);
}
catch (FileNotFoundException ex)
{
    // expected missing file — recreate or skip
}

Prevention

When it happens

Trigger: Calling IFileStorage.OpenReadFile with a relative path that does not exist under AppCacheDirectory; an absolute path to a missing file; a file deleted between the existence check and the open (TOCTOU); a path that points into a location the packaged app cannot reach without broker access.

Common situations: MSIX/sandboxed app cache layout differing from dev; a file expected from a previous run that was cleaned on update; path with forward slashes or case that resolves differently; producer step failed so the file was never written.

Related errors

AI-assisted analysis of DevToys-app/DevToys@7e12df8448 (2026-08-13). Data as JSON: /api/errors/8afa13afe18e2c0a. Report an issue: GitHub.

Appendix: source

Thrown at src/app/dev/platforms/desktop/DevToys.Windows/Core/FileStorage.cs:36

    {
        if (!Path.IsPathRooted(relativeOrAbsoluteFilePath))
        {
            relativeOrAbsoluteFilePath = Path.Combine(AppCacheDirectory, relativeOrAbsoluteFilePath);
        }

        return File.Exists(relativeOrAbsoluteFilePath);
    }

    public FileStream OpenReadFile(string relativeOrAbsoluteFilePath)
    {
        if (!Path.IsPathRooted(relativeOrAbsoluteFilePath))
        {
            relativeOrAbsoluteFilePath = Path.Combine(AppCacheDirectory, relativeOrAbsoluteFilePath);
        }

        if (!File.Exists(relativeOrAbsoluteFilePath))
        {
            throw new FileNotFoundException("Unable to find the indicated file.", relativeOrAbsoluteFilePath);
        }

        return new FileStream(relativeOrAbsoluteFilePath, FileMode.Open, FileAccess.Read, FileShare.Read, SandboxedFileReader.BufferSize, FileOptions.Asynchronous | FileOptions.SequentialScan);
    }

    public FileStream OpenWriteFile(string relativeOrAbsoluteFilePath, bool replaceIfExist)
    {
        if (!Path.IsPathRooted(relativeOrAbsoluteFilePath))
        {
            relativeOrAbsoluteFilePath = Path.Combine(AppCacheDirectory, relativeOrAbsoluteFilePath);
        }

        if (File.Exists(relativeOrAbsoluteFilePath) && replaceIfExist)
        {
            File.Delete(relativeOrAbsoluteFilePath);
        }

        string parentDirectory = Path.GetDirectoryName(relativeOrAbsoluteFilePath)!;

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