error building app with hermes: '..' is not recognized as an internal or external command

Question

• Building the react-native app on Windows 10.

• The error is printed for line 165 of node_modules\react-native\react.gradle:

'..' is not recognized as an internal or external command, operable program or batch file

Line 165 is the 5th line in the following, starting with exec:

if (enableHermes) {
                doLast {
                    def hermesFlags;
                    def hbcTempFile = file("${jsBundleFile}.hbc")
                    exec {
                        if (targetName.toLowerCase().contains("release")) {
                            // Can't use ?: since that will also substitute valid empty lists
                            hermesFlags = config.hermesFlagsRelease
                            if (hermesFlags == null) hermesFlags = ["-O", "-output-source-map"]
                        } else {
                            hermesFlags = config.hermesFlagsDebug
                            if (hermesFlags == null) hermesFlags = []
                        }

                        if (Os.isFamily(Os.FAMILY_WINDOWS)) {
                            commandLine("cmd", "/c", getHermesCommand(), "-emit-binary", "-out", hbcTempFile, jsBundleFile, *hermesFlags)
                        } else {
                            commandLine(getHermesCommand(), "-emit-binary", "-out", hbcTempFile, jsBundleFile, *hermesFlags)
                        }
                    }
                    ant.move(
                        file: hbcTempFile,
                        toFile: jsBundleFile
                    );
                    if (hermesFlags.contains("-output-source-map")) {
                        ant.move(
                            // Hermes will generate a source map with this exact name
                            file: "${jsBundleFile}.hbc.map",
                            tofile: jsCompilerSourceMapFile
                        );
                        exec {
                            // TODO: set task dependencies for caching

                            // Set up the call to the compose-source-maps script
                            workingDir(reactRoot)
                            if (Os.isFamily(Os.FAMILY_WINDOWS)) {
                                commandLine("cmd", "/c", *nodeExecutableAndArgs, composeSourceMapsPath, jsPackagerSourceMapFile, jsCompilerSourceMapFile, "-o", jsOutputSourceMapFile)
                            } else {
                                commandLine(*nodeExecutableAndArgs, composeSourceMapsPath, jsPackagerSourceMapFile, jsCompilerSourceMapFile, "-o", jsOutputSourceMapFile)
                            }
                        }
                    }
                }
            }

Here is the definition of hermescommand in android/app/build.gradle:

project.ext.react = [
    enableHermes: true,  // clean and rebuild if changing
    // next added by Yossi
    hermesCommand: "../../node_modules/hermesengine/win64-bin/hermes",
    extraPackagerArgs: ["--sourcemap-output", "$buildDir/intermediates/assets/release/index.android.bundle.map"]
]

Which, as far as I understand, points to the following file:

node_modules\hermes-engine\win64-bin\hermes.exe

Any idea?

Updated definition in android/app/build.gradle (following the answer below):

project.ext.react = [
    enableHermes: true,  // clean and rebuild if changing
    // -either- hermesCommand: "..\\..\\node_modules\\hermesengine\\win64-bin\\hermes",
    // -or- hermesCommand: "../../node_modules/hermesengine/%OS-BIN%/hermes",
    hermesCommand: "../../node_modules/hermesengine/%OS-BIN%/hermes",
    extraPackagerArgs: ["--sourcemap-output", "$buildDir/intermediates/assets/release/index.android.bundle.map"]
]

The build output now, after the change, is the following:

> Task :app:bundleReleaseJsAndAssets
warning: the transform cache was reset.
                 Welcome to React Native!
                Learn once, write anywhere


info Writing bundle output to:, C:\esites-grocery\test1\plumpclient\android\app\build\generated\assets\react\release\index.android.bundle
info Writing sourcemap output to:, C:\esites-grocery\test1\plumpclient\android\app\build/intermediates/assets/release/index.android.bundle.map
info Done writing bundle output
info Done writing sourcemap output
info Copying 141 asset files
info Done copying assets
The system cannot find the path specified.

> Task :app:bundleReleaseJsAndAssets FAILED

> Task :app:bundleReleaseJsAndAssets_SentryUpload_3001
Processing react-native sourcemaps for Sentry upload.
> Analyzing 2 sources
> Rewriting sources
> Adding source map references
Uploading sourcemaps for release com.plumpplum@RN62 Hermes+3001 distribution 3001
> Bundled 2 files for upload
> Uploaded release files to Sentry
> File upload complete

Source Map Upload Report
  Minified Scripts
    ~/index.android.bundle (sourcemap at index.android.bundle.map)
  Source Maps
    ~/index.android.bundle.map

> Task :app:bundleReleaseJsAndAssets_SentryUpload_1001
Processing react-native sourcemaps for Sentry upload.
> Analyzing 2 sources
> Rewriting sources
> Adding source map references
Uploading sourcemaps for release com.plumpplum@RN62 Hermes+1001 distribution 1001
> Bundled 2 files for upload
> Uploaded release files to Sentry
> File upload complete

Source Map Upload Report
  Minified Scripts
    ~/index.android.bundle (sourcemap at index.android.bundle.map)
  Source Maps
    ~/index.android.bundle.map

> Task :app:bundleReleaseJsAndAssets_SentryUpload_2001
Processing react-native sourcemaps for Sentry upload.
> Analyzing 2 sources
> Rewriting sources
> Adding source map references
Uploading sourcemaps for release com.plumpplum@RN62 Hermes+2001 distribution 2001
> Bundled 2 files for upload
> Uploaded release files to Sentry
> File upload complete

Source Map Upload Report
  Minified Scripts
    ~/index.android.bundle (sourcemap at index.android.bundle.map)
  Source Maps
    ~/index.android.bundle.map

> Task :app:bundleReleaseJsAndAssets_SentryUpload_4001
Processing react-native sourcemaps for Sentry upload.
> Analyzing 2 sources
> Rewriting sources
> Adding source map references
Uploading sourcemaps for release com.plumpplum@RN62 Hermes+4001 distribution 4001
> Bundled 2 files for upload
> Uploaded release files to Sentry
> File upload complete

Source Map Upload Report
  Minified Scripts
    ~/index.android.bundle (sourcemap at index.android.bundle.map)
  Source Maps
    ~/index.android.bundle.map

FAILURE: Build failed with an exception.

* Where:
Script 'C:\esites-grocery\test1\plumpclient\node_modules\react-native\react.gradle' line: 165

* What went wrong:
Execution failed for task ':app:bundleReleaseJsAndAssets'.
> Process 'command 'cmd'' finished with non-zero exit value 1

Answer 1

Here's more of react.gradle:

def getHermesCommand = {
    // If the project specifies a Hermes command, don't second guess it.
    if (!hermesCommand.contains("%OS-BIN%")) {
        return hermesCommand
    }

    // Execution on Windows fails with / as separator
    return hermesCommand
            .replaceAll("%OS-BIN%", getHermesOSBin())
            .replace('/' as char, File.separatorChar);
}

You are specifying ../../node_modules/hermesengine/win64-bin/hermes as the path, which is OS specific (as determined by not having an OS placeholder).

As per the comment, react.gradle therefore doesn't second guess your path and just passes it directly to the OS command interpreter.

This fails because your command interpreter does not allow / as directory separator.

Either specify a path that's valid for your system:

hermesCommand: "..\\..\\node_modules\\hermesengine\\win64-bin\\hermes",

Or specify an OS-independent path to let react.gradle transform it for each platform:

hermesCommand: "../../node_modules/hermesengine/%OS-BIN%/hermes",