diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/ConvertTool.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/ConvertTool.kt
index e2f176df..498fd4a1 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/ConvertTool.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/ConvertTool.kt
@@ -86,14 +86,6 @@ fun main(args: Array<String>) {
                     printErrorAndTerminate("Folder does not exist: ${destinationPath.toAbsolutePath()}")
                 }
 
-                if (!destinationPath.isEmptyExceptForHidden()) {
-                    if (!overwrite) {
-                        error("the destination $destinationPath folder is not empty, call converter with --overwrite to overwrite it")
-                    } else {
-                        destinationPath.deleteNonHiddenRecursively()
-                    }
-                }
-
                 if (finalSource != null) {
                     RecipeConverter(
                         agpVersion = agpVersion,
@@ -104,9 +96,20 @@ fun main(args: Array<String>) {
                         branchRoot = branchRoot,
                     ).convert(
                         source = Path.of(finalSource),
-                        destination = destinationPath
+                        destination = destinationPath,
+                        overwrite = overwrite
                     )
                 } else if (finalSourceAll != null) {
+                    // if we do a convert all then we expect the root folder to be (mostly) empty
+                    // (hidden files, like git files, are kept)
+                    if (!destinationPath.isEmptyExceptForHidden()) {
+                        if (!overwrite) {
+                            printErrorAndTerminate("the destination $destinationPath folder is not empty, call converter with --overwrite to overwrite it")
+                        } else {
+                            destinationPath.deleteNonHiddenRecursively()
+                        }
+                    }
+
                     RecursiveConverter(
                         agpVersion = agpVersion,
                         repoLocation = repoLocation,
@@ -136,7 +139,7 @@ fun main(args: Array<String>) {
 
                 // check the env var for the SDK exist
                 if (System.getenv("ANDROID_HOME") == null) {
-                    throw RuntimeException("To run $COMMAND_VALIDATE command, the environment variable ANDROID_HOME must be set and must point to your Android SDK.")
+                    printErrorAndTerminate("To run $COMMAND_VALIDATE command, the environment variable ANDROID_HOME must be set and must point to your Android SDK.")
                 }
 
                 if (mode != null) {
@@ -233,15 +236,18 @@ private fun validateNullArg(arg: Any?, msg: String) {
     }
  }
 
-private fun printErrorAndTerminate(msg: String): Nothing {
+fun printErrorAndTerminate(msg: String): Nothing {
     System.err.println(msg)
+    if (System.getenv("CONVERT_DEBUG") != null) {
+        throw RuntimeException("error. See console output")
+    }
     exitProcess(1)
 }
 
 private fun Path.isEmptyExceptForHidden(): Boolean = !Files.list(this).anyMatch { !it.name.startsWith('.') }
 
 @OptIn(ExperimentalPathApi::class)
-private fun Path.deleteNonHiddenRecursively() {
+fun Path.deleteNonHiddenRecursively() {
     Files.list(this).filter {
         !it.name.startsWith('.')
     }.forEach {
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/Converter.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/Converter.kt
index 52ec3e01..365d6985 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/Converter.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/Converter.kt
@@ -16,6 +16,7 @@
 
 package com.google.android.gradle_recipe.converter.converters
 
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import com.google.android.gradle_recipe.converter.recipe.RecipeData
 import com.google.android.gradle_recipe.converter.recipe.toMajorMinor
 import java.nio.file.Files
@@ -79,7 +80,7 @@ abstract class Converter(
     fun copyGradleFolder(dest: Path) {
         val source = branchRoot.resolve(GRADLE_RESOURCES_FOLDER)
         if (!source.isDirectory()) {
-            throw RuntimeException("Unable to find gradle resources at $source")
+            printErrorAndTerminate("Unable to find gradle resources at $source")
         }
 
         dest.mkdirs()
@@ -104,11 +105,11 @@ abstract class Converter(
     protected fun getMinAgp(): String = recipeData?.minAgpVersion
         // this really should not happen
         // TODO(b/317888166) improve this
-        ?: error("recipeData not loaded in Converter")
+        ?: printErrorAndTerminate("recipeData not loaded in Converter")
 
     protected fun getVersionInfoFromAgp(agpVersion: String): VersionInfo {
         val agp = agpVersion.toMajorMinor()
         return getVersionsFromAgp(branchRoot, agp)
-            ?: throw RuntimeException("Unable to fetch VersionInfo for AGP $agp")
+            ?: printErrorAndTerminate("Unable to fetch VersionInfo for AGP $agp")
     }
 }
\ No newline at end of file
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ConverterUtils.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ConverterUtils.kt
index 880ee416..0af3b8f7 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ConverterUtils.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ConverterUtils.kt
@@ -16,6 +16,7 @@
 
 package com.google.android.gradle_recipe.converter.converters
 
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import java.nio.file.Path
 
 /**
@@ -31,7 +32,7 @@ fun Path.mkdirs(): Boolean {
     val ret = file.mkdirs()
     if (!ret) {
         if (!file.isDirectory) {
-            throw RuntimeException("Unable to create folder: $this")
+            printErrorAndTerminate("Unable to create folder: $this")
         }
     }
     return ret
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecipeConverter.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecipeConverter.kt
index b9c2c4b9..2bd61c86 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecipeConverter.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecipeConverter.kt
@@ -15,17 +15,20 @@
  */
 package com.google.android.gradle_recipe.converter.converters
 
+import com.google.android.gradle_recipe.converter.deleteNonHiddenRecursively
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import com.google.android.gradle_recipe.converter.recipe.RecipeData
 import com.google.android.gradle_recipe.converter.recipe.toMajorMinor
 import java.io.File
-import java.io.IOException
 import java.lang.System.err
-import java.nio.file.*
+import java.nio.file.FileVisitResult
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.SimpleFileVisitor
+import java.nio.file.StandardCopyOption
 import java.nio.file.attribute.BasicFileAttributes
-import kotlin.io.path.exists
 import kotlin.io.path.isDirectory
 import kotlin.io.path.isRegularFile
-import kotlin.io.path.name
 import kotlin.io.path.readLines
 
 private const val VERSION_MAPPING = "version_mappings.txt"
@@ -57,7 +60,7 @@ private fun initAgpToGradleMap(branchRoot: Path) {
     if (!::agpToVersionsMap.isInitialized) {
         val file = branchRoot.resolve(VERSION_MAPPING)
         if (!file.isRegularFile()) {
-            throw RuntimeException("Missing AGP version mapping file at $file")
+            printErrorAndTerminate("Missing AGP version mapping file at $file")
         }
 
         val lines = file
@@ -141,7 +144,7 @@ class RecipeConverter(
 
             Mode.RELEASE -> {
                 ReleaseConverter(
-                    agpVersion = agpVersion ?: error("Must specify the AGP version for release"),
+                    agpVersion = agpVersion ?: printErrorAndTerminate("Must specify the AGP version for release"),
                     gradleVersion = gradleVersion,
                     repoLocation = repoLocation,
                     gradlePath = gradlePath,
@@ -158,15 +161,27 @@ class RecipeConverter(
      * @param destination the destination folder. A new folder will be created inside to contain the recipe
      *
      */
-    fun convert(source: Path, destination: Path): ConversionResult {
+    fun convert(source: Path, destination: Path, overwrite: Boolean = false): ConversionResult {
         if (!source.isDirectory()) {
-            error("the source $source folder is not a directory")
+            printErrorAndTerminate("Source $source is not a directory!")
         }
 
         val recipeData = RecipeData.loadFrom(source, mode)
 
         val recipeDestination = destination.resolve(recipeData.destinationFolder)
 
+        if (recipeDestination.isRegularFile()) {
+            printErrorAndTerminate("Destination $recipeDestination exist but is not a folder!")
+        }
+
+        if (recipeDestination.isDirectory() && recipeDestination.isNotEmpty()) {
+            if (!overwrite) {
+                printErrorAndTerminate("Destination $recipeDestination folder is not empty, call converter with --overwrite to overwrite it")
+            } else {
+                recipeDestination.deleteNonHiddenRecursively()
+            }
+        }
+
         val success = if (converter.isConversionCompliant(recipeData)) {
             converter.recipeData = recipeData
 
@@ -232,4 +247,6 @@ class RecipeConverter(
 
         return ConversionResult(recipeData, success)
     }
-}
\ No newline at end of file
+}
+
+private fun Path.isNotEmpty(): Boolean = Files.list(this).findAny().isPresent
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecursiveConverter.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecursiveConverter.kt
index da2d49de..438eb8da 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecursiveConverter.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/RecursiveConverter.kt
@@ -17,6 +17,7 @@
 package com.google.android.gradle_recipe.converter.converters
 
 import com.google.android.gradle_recipe.converter.converters.RecipeConverter.Mode
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import com.google.android.gradle_recipe.converter.recipe.visitRecipes
 import java.io.File
 import java.io.IOException
@@ -45,10 +46,9 @@ class RecursiveConverter(
         val link: String
     )
 
-    @Throws(IOException::class)
     fun convertAllRecipes(sourceAll: Path, destination: Path) {
         if (!sourceAll.exists()) {
-            error("the source $sourceAll folder doesn't exist")
+            printErrorAndTerminate("the source $sourceAll folder doesn't exist")
         }
 
         val recipeConverter = RecipeConverter(
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ReleaseConverter.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ReleaseConverter.kt
index d7ed51cb..2a0befd9 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ReleaseConverter.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/converters/ReleaseConverter.kt
@@ -16,6 +16,7 @@
 
 package com.google.android.gradle_recipe.converter.converters
 
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import com.google.android.gradle_recipe.converter.recipe.RecipeData
 import java.nio.file.Files
 import java.nio.file.Path
@@ -48,8 +49,8 @@ class ReleaseConverter(
 
         } else {
             // internal CI release
-            pathToAgpRepo = repoLocation ?: error("must specify path to repo")
-            pathToGradle = gradlePath ?: error("must specify path to Gradle")
+            pathToAgpRepo = repoLocation ?: printErrorAndTerminate("must specify path to repo")
+            pathToGradle = gradlePath ?: printErrorAndTerminate("must specify path to Gradle")
         }
     }
 
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeData.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeData.kt
index ef5a8289..4f07d96f 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeData.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeData.kt
@@ -18,6 +18,7 @@ package com.google.android.gradle_recipe.converter.recipe
 
 import com.github.rising3.semver.SemVer
 import com.google.android.gradle_recipe.converter.converters.RecipeConverter
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import org.tomlj.Toml
 import org.tomlj.TomlParseResult
 import java.io.File
@@ -59,7 +60,7 @@ class RecipeData private constructor(
             if (parseResult.hasErrors()) {
                 System.err.println("TOML Parsing error(s) for $toml:")
                 parseResult.errors().forEach { error -> System.err.println(error.toString()) }
-                throw IllegalArgumentException("Unable to read $toml")
+                printErrorAndTerminate("Unable to read $toml")
             }
 
             val indexName = if (mode == RecipeConverter.Mode.RELEASE) {
@@ -80,7 +81,7 @@ class RecipeData private constructor(
                 } else {
                     // check there's no path separator in there
                     if (entry.contains('/')) {
-                        error("destinationFolder value ('$entry') cannot contain / character ($recipeFolder)")
+                        printErrorAndTerminate("destinationFolder value ('$entry') cannot contain / character ($recipeFolder)")
                     }
                     entry
                 }
@@ -92,7 +93,7 @@ class RecipeData private constructor(
                 indexName = indexName,
                 destinationFolder = destinationFolder,
                 minAgpVersion = parseResult.getString("agpVersion.min")
-                    ?: error("Did not find mandatory 'agpVersion.min' in $toml"),
+                    ?: printErrorAndTerminate("Did not find mandatory 'agpVersion.min' in $toml"),
                 maxAgpVersion = parseResult.getString("agpVersion.max"),
                 tasks = parseResult.getArray("gradleTasks.tasks")?.toList()?.map { it as String } ?: emptyList(),
                 keywords = parseResult.getArray("indexMetadata.index")?.toList()?.map { it as String } ?: emptyList()
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeUtils.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeUtils.kt
index 06038cc0..bb5b9a75 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeUtils.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/recipe/RecipeUtils.kt
@@ -16,6 +16,7 @@
 
 package com.google.android.gradle_recipe.converter.recipe
 
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import java.nio.file.Files
 import java.nio.file.Path
 import kotlin.io.path.exists
@@ -26,7 +27,7 @@ import kotlin.io.path.isHidden
  */
 fun visitRecipes(rootFolder: Path, recipeCallback: (Path) -> Unit) {
     if (!rootFolder.exists()) {
-        error("the source $rootFolder folder doesn't exist")
+        printErrorAndTerminate("the source $rootFolder folder doesn't exist")
     }
 
     Files.walk(rootFolder).filter { currentPath: Path ->
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/InternalCIValidator.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/InternalCIValidator.kt
index a7ddd4b4..a9d79ee2 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/InternalCIValidator.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/InternalCIValidator.kt
@@ -32,7 +32,6 @@ class InternalCIValidator(
     private val gradlePath: String,
     private val branchRoot: Path,
 ) {
-    @Throws(IOException::class)
     fun validate(sourceAll: Path, tmpFolder: Path?) {
 
         val converter = RecipeConverter(
diff --git a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/MinMaxCurrentAgpValidator.kt b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/MinMaxCurrentAgpValidator.kt
index 7893a1a0..22487dec 100644
--- a/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/MinMaxCurrentAgpValidator.kt
+++ b/convert-tool/app/src/main/kotlin/com/google/android/gradle_recipe/converter/validators/MinMaxCurrentAgpValidator.kt
@@ -20,6 +20,7 @@ import com.google.android.gradle_recipe.converter.converters.RecipeConverter
 import com.google.android.gradle_recipe.converter.converters.RecipeConverter.Mode
 import com.google.android.gradle_recipe.converter.converters.getMaxAgp
 import com.google.android.gradle_recipe.converter.converters.getVersionsFromAgp
+import com.google.android.gradle_recipe.converter.printErrorAndTerminate
 import com.google.android.gradle_recipe.converter.recipe.RecipeData
 import com.google.android.gradle_recipe.converter.recipe.toMajorMinor
 import java.nio.file.Path
@@ -50,7 +51,7 @@ class MinMaxCurrentAgpValidator(
         agpVersion: String,
     ) {
         val gradleVersion = getVersionsFromAgp(branchRoot, agpVersion.toMajorMinor())?.gradle
-            ?: throw RuntimeException("Unable to find Gradle version for AGP version $agpVersion - Make sure it's present in version_mappings.txt")
+            ?: printErrorAndTerminate("Unable to find Gradle version for AGP version $agpVersion - Make sure it's present in version_mappings.txt")
 
         val recipeConverter = RecipeConverter(
             agpVersion = agpVersion,