diff --git a/app/src/main/java/com/itsaky/androidide/activities/editor/ProjectHandlerActivity.kt b/app/src/main/java/com/itsaky/androidide/activities/editor/ProjectHandlerActivity.kt
index cd3361e4c..05db7993e 100644
--- a/app/src/main/java/com/itsaky/androidide/activities/editor/ProjectHandlerActivity.kt
+++ b/app/src/main/java/com/itsaky/androidide/activities/editor/ProjectHandlerActivity.kt
@@ -50,6 +50,10 @@ import com.itsaky.androidide.tasks.executeWithProgress
 import com.itsaky.androidide.tooling.api.messages.AndroidInitializationParams
 import com.itsaky.androidide.tooling.api.messages.InitializeProjectParams
 import com.itsaky.androidide.tooling.api.messages.result.InitializeResult
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_DIRECTORY_INACCESSIBLE
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_NOT_DIRECTORY
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_NOT_FOUND
 import com.itsaky.androidide.tooling.api.models.BuildVariantInfo
 import com.itsaky.androidide.tooling.api.models.mapToSelectedVariants
 import com.itsaky.androidide.utils.DURATION_INDEFINITE
@@ -394,7 +398,7 @@ abstract class ProjectHandlerActivity : BaseEditorActivity() {
       if (result == null || !result.isSuccessful || error != null) {
         log.error("An error occurred initializing the project with Tooling API", error)
         ThreadUtils.runOnUiThread {
-          postProjectInit(false)
+          postProjectInit(false, result?.failure)
         }
         return@whenCompleteAsync
       }
@@ -464,7 +468,9 @@ abstract class ProjectHandlerActivity : BaseEditorActivity() {
       manager.notifyProjectUpdate()
       updateBuildVariants(manager.androidBuildVariants)
 
-      com.itsaky.androidide.tasks.runOnUiThread { postProjectInit(true) }
+      com.itsaky.androidide.tasks.runOnUiThread {
+        postProjectInit(true, null)
+      }
     }
   }
 
@@ -473,11 +479,23 @@ abstract class ProjectHandlerActivity : BaseEditorActivity() {
     editorViewModel.isInitializing = true
   }
 
-  protected open fun postProjectInit(isSuccessful: Boolean) {
+  protected open fun postProjectInit(isSuccessful: Boolean, failure: TaskExecutionResult.Failure?) {
     val manager = ProjectManagerImpl.getInstance()
     if (!isSuccessful) {
-      setStatus(getString(string.msg_project_initialization_failed))
-      flashError(string.msg_project_initialization_failed)
+      val initFailed = getString(string.msg_project_initialization_failed)
+      setStatus(initFailed)
+
+      val msg = when(failure) {
+        PROJECT_DIRECTORY_INACCESSIBLE -> string.msg_project_dir_inaccessible
+        PROJECT_NOT_DIRECTORY -> string.msg_file_is_not_dir
+        PROJECT_NOT_FOUND -> string.msg_project_dir_doesnt_exist
+        else -> null
+      }?.let {
+        "$initFailed: ${getString(it)}"
+      }
+
+      flashError(msg ?: initFailed)
+
       editorViewModel.isInitializing = false
       manager.projectInitialized = false
       return
diff --git a/resources/src/main/res/values/strings.xml b/resources/src/main/res/values/strings.xml
index 96e75f770..c6d800f72 100644
--- a/resources/src/main/res/values/strings.xml
+++ b/resources/src/main/res/values/strings.xml
@@ -622,4 +622,7 @@
   <string name="idepref_general_localeSelector_title">Language</string>
   <string name="idepref_general_localeSelector_summary">Select a language for AndroidIDE.</string>
   <string name="locale_system_default">System Default</string>
+  <string name="msg_project_dir_inaccessible">Project directory is not accessible</string>
+  <string name="msg_file_is_not_dir">Selected file is not a directory</string>
+  <string name="msg_project_dir_doesnt_exist">Project directory does not exist</string>
 </resources>
diff --git a/subprojects/projects/src/main/java/com/itsaky/androidide/projects/ProjectManagerImpl.kt b/subprojects/projects/src/main/java/com/itsaky/androidide/projects/ProjectManagerImpl.kt
index 361fe6535..6d0b6fd72 100644
--- a/subprojects/projects/src/main/java/com/itsaky/androidide/projects/ProjectManagerImpl.kt
+++ b/subprojects/projects/src/main/java/com/itsaky/androidide/projects/ProjectManagerImpl.kt
@@ -219,6 +219,10 @@ class ProjectManagerImpl : IProjectManager, EventReceiver {
       return
     }
 
+    if (builder.isBuildInProgress) {
+      return
+    }
+
     val tasks = getAndroidModules().flatMap { module ->
       val variant = module.getSelectedVariant()
       if (variant == null) {
diff --git a/subprojects/tooling-api-impl/src/main/java/com/itsaky/androidide/tooling/impl/ToolingApiServerImpl.kt b/subprojects/tooling-api-impl/src/main/java/com/itsaky/androidide/tooling/impl/ToolingApiServerImpl.kt
index fe8a77373..fdf4d9668 100644
--- a/subprojects/tooling-api-impl/src/main/java/com/itsaky/androidide/tooling/impl/ToolingApiServerImpl.kt
+++ b/subprojects/tooling-api-impl/src/main/java/com/itsaky/androidide/tooling/impl/ToolingApiServerImpl.kt
@@ -35,6 +35,10 @@ import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Fai
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.BUILD_FAILED
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.CONNECTION_CLOSED
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.CONNECTION_ERROR
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_DIRECTORY_INACCESSIBLE
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_NOT_DIRECTORY
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_NOT_FOUND
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.PROJECT_NOT_INITIALIZED
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.UNKNOWN
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.UNSUPPORTED_BUILD_ARGUMENT
 import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult.Failure.UNSUPPORTED_CONFIGURATION
@@ -57,7 +61,6 @@ import org.gradle.tooling.internal.consumer.DefaultGradleConnector
 import java.io.File
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.CompletionException
-import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.system.exitProcess
 
 /**
@@ -68,7 +71,6 @@ import kotlin.system.exitProcess
 internal class ToolingApiServerImpl(private val project: ProjectImpl) :
   IToolingApiServer {
 
-  private val _isInitialized = AtomicBoolean(false)
   private var client: IToolingApiClient? = null
   private var connector: GradleConnector? = null
   private var connection: ProjectConnection? = null
@@ -79,9 +81,13 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
   /**
    * Whether the project has been initialized or not.
    */
-  var isInitialized: Boolean
-    get() = _isInitialized.get()
-    private set(value) = _isInitialized.set(value)
+  var isInitialized: Boolean = false
+    private set
+
+  /**
+   * Whether a build or project synchronization is in progress.
+   */
+  private var isBuildInProgress: Boolean = false
 
   /**
    * Whether the server has a live connection to Gradle.
@@ -102,7 +108,7 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
   }
 
   override fun initialize(params: InitializeProjectParams): CompletableFuture<InitializeResult> {
-    return CompletableFuture.supplyAsync {
+    return runBuild {
       try {
         log.debug("Got initialize request", params)
 
@@ -112,6 +118,14 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
           cancelCurrentBuild().get()
         }
 
+        val projectDirectory = File(params.directory)
+        val failureReason = validateProjectDirectory(projectDirectory)
+
+        if (failureReason != null) {
+          log.error("Cannot initialize project: $failureReason")
+          return@runBuild InitializeResult(false, failureReason)
+        }
+
         val stopWatch = StopWatch("Connection to project")
         val isReinitializing = connector != null && connection != null && params == lastInitParams
 
@@ -123,7 +137,7 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
           // or the project is being initialized with different parameters
           connector?.disconnect()
 
-          connector = GradleConnector.newConnector().forProjectDirectory(File(params.directory))
+          connector = GradleConnector.newConnector().forProjectDirectory(projectDirectory)
           setupConnectorForGradleInstallation(this.connector!!, params.gradleDistribution)
           stopWatch.lap("Connector created")
         }
@@ -163,15 +177,24 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
         this.isInitialized = true
 
         notifyBuildSuccess(emptyList())
-        return@supplyAsync InitializeResult(true)
+        return@runBuild InitializeResult(true)
       } catch (err: Throwable) {
         log.error("Failed to initialize project", err)
         notifyBuildFailure(emptyList())
-        return@supplyAsync InitializeResult(false)
+        return@runBuild InitializeResult(false, getTaskFailureType(err))
       }
     }
   }
 
+  private fun validateProjectDirectory(
+    projectDirectory: File
+  ) = when {
+    !projectDirectory.exists() -> PROJECT_NOT_FOUND
+    !projectDirectory.isDirectory -> PROJECT_NOT_DIRECTORY
+    !projectDirectory.canRead() -> PROJECT_DIRECTORY_INACCESSIBLE
+    else -> null
+  }
+
   override fun isServerInitialized(): CompletableFuture<Boolean> {
     return CompletableFuture.supplyAsync { isInitialized }
   }
@@ -184,8 +207,21 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
   }
 
   override fun executeTasks(message: TaskExecutionMessage): CompletableFuture<TaskExecutionResult> {
-    return CompletableFuture.supplyAsync {
-      assertProjectInitialized()
+    return runBuild {
+      if (!isServerInitialized().get()) {
+        log.error("Cannot execute tasks: $PROJECT_NOT_INITIALIZED")
+        return@runBuild TaskExecutionResult(false, PROJECT_NOT_INITIALIZED)
+      }
+
+      val lastInitParams = this.lastInitParams
+      if (lastInitParams != null) {
+        val projectDirectory = File(lastInitParams.directory)
+        val failureReason = validateProjectDirectory(projectDirectory)
+        if (failureReason != null) {
+          log.error("Cannot execute tasks: $failureReason")
+          return@runBuild TaskExecutionResult(isSuccessful = false, failureReason)
+        }
+      }
 
       log.debug("Received request to run tasks.", message)
 
@@ -215,10 +251,10 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
         builder.run()
         this.buildCancellationToken = null
         notifyBuildSuccess(message.tasks)
-        return@supplyAsync TaskExecutionResult.SUCCESS
+        return@runBuild TaskExecutionResult.SUCCESS
       } catch (error: Throwable) {
         notifyBuildFailure(message.tasks)
-        return@supplyAsync TaskExecutionResult(false, getTaskFailureType(error), error.message)
+        return@runBuild TaskExecutionResult(false, getTaskFailureType(error))
       }
     }
   }
@@ -330,6 +366,26 @@ internal class ToolingApiServerImpl(private val project: ProjectImpl) :
       else -> UNKNOWN
     }
 
+  private inline fun <T : Any?> supplyAsync(crossinline action: () -> T): CompletableFuture<T> =
+    CompletableFuture.supplyAsync {
+      action()
+    }
+
+  private inline fun <T : Any?> runBuild(crossinline action: () -> T): CompletableFuture<T> =
+    supplyAsync {
+      if (isBuildInProgress) {
+        log.error("Cannot run build, build is already in prorgess!")
+        throw IllegalStateException("Build is already in progress")
+      }
+
+      isBuildInProgress = true
+      try {
+        action()
+      } finally {
+        isBuildInProgress = false
+      }
+    }
+
   private fun assertProjectInitialized() {
     if (!isServerInitialized().get()) {
       throw CompletionException(IllegalStateException("Project is not initialized!"))
diff --git a/subprojects/tooling-api-impl/src/test/java/com/itsaky/androidide/tooling/impl/MultiModuleAndroidProjectTest.kt b/subprojects/tooling-api-impl/src/test/java/com/itsaky/androidide/tooling/impl/MultiModuleAndroidProjectTest.kt
index 2e74c7caa..f38b9e056 100644
--- a/subprojects/tooling-api-impl/src/test/java/com/itsaky/androidide/tooling/impl/MultiModuleAndroidProjectTest.kt
+++ b/subprojects/tooling-api-impl/src/test/java/com/itsaky/androidide/tooling/impl/MultiModuleAndroidProjectTest.kt
@@ -28,6 +28,7 @@ import com.itsaky.androidide.tooling.api.IProject
 import com.itsaky.androidide.tooling.api.IToolingApiServer
 import com.itsaky.androidide.tooling.api.ProjectType
 import com.itsaky.androidide.tooling.api.messages.TaskExecutionMessage
+import com.itsaky.androidide.tooling.api.messages.result.TaskExecutionResult
 import com.itsaky.androidide.tooling.api.models.AndroidProjectMetadata
 import com.itsaky.androidide.tooling.api.models.JavaModuleExternalDependency
 import com.itsaky.androidide.tooling.api.models.JavaModuleProjectDependency
@@ -37,11 +38,22 @@ import com.itsaky.androidide.tooling.events.ProgressEvent
 import com.itsaky.androidide.tooling.events.task.TaskStartEvent
 import com.itsaky.androidide.tooling.testing.ToolingApiTestLauncher
 import com.itsaky.androidide.tooling.testing.ToolingApiTestLauncher.MultiVersionTestClient
+import com.itsaky.androidide.utils.FileProvider
 import com.itsaky.androidide.utils.ILogger
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.junit.runners.JUnit4
+import java.nio.file.Paths
+import java.nio.file.attribute.PosixFilePermission
 import java.util.concurrent.CompletableFuture
+import kotlin.io.path.ExperimentalPathApi
+import kotlin.io.path.createDirectories
+import kotlin.io.path.createFile
+import kotlin.io.path.deleteIfExists
+import kotlin.io.path.deleteRecursively
+import kotlin.io.path.exists
+import kotlin.io.path.setPosixFilePermissions
+import kotlin.io.path.writeText
 
 /** @author Akash Yadav */
 @RunWith(JUnit4::class)
@@ -54,6 +66,26 @@ class MultiModuleAndroidProjectTest {
     doAssertions(project, server)
   }
 
+  @Test
+  fun `test non-existing project initialization`() {
+    val (_, _, result) = ToolingApiTestLauncher().launchServer(
+      projectDir = Paths.get("/directory/does/not/exist/"))
+    assertThat(result?.isSuccessful).isFalse()
+    assertThat(result?.failure).isEqualTo(TaskExecutionResult.Failure.PROJECT_NOT_FOUND)
+  }
+
+  @Test
+  fun `test project initialization with file path`() {
+    val path = FileProvider.projectRoot().resolve("build").resolve("should-be-directory.txt")
+    path.deleteIfExists()
+    path.createFile()
+
+    val (_, _, result) = ToolingApiTestLauncher().launchServer(
+      projectDir = path)
+    assertThat(result?.isSuccessful).isFalse()
+    assertThat(result?.failure).isEqualTo(TaskExecutionResult.Failure.PROJECT_NOT_DIRECTORY)
+  }
+
   @Test
   fun `test task name should be shown if gradle configuration cache is enabled`() {
 
diff --git a/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/InitializeResult.kt b/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/InitializeResult.kt
index 874c75980..2a3ca7820 100644
--- a/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/InitializeResult.kt
+++ b/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/InitializeResult.kt
@@ -23,4 +23,4 @@ package com.itsaky.androidide.tooling.api.messages.result
  * @param isSuccessful Whether the project initialization was successful.
  * @author Akash Yadav
  */
-class InitializeResult(val isSuccessful: Boolean)
+class InitializeResult(val isSuccessful: Boolean, val failure: TaskExecutionResult.Failure? = TaskExecutionResult.Failure.UNKNOWN)
diff --git a/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/TaskExecutionResult.kt b/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/TaskExecutionResult.kt
index 551860258..81d5452a4 100644
--- a/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/TaskExecutionResult.kt
+++ b/subprojects/tooling-api/src/main/java/com/itsaky/androidide/tooling/api/messages/result/TaskExecutionResult.kt
@@ -22,11 +22,10 @@ package com.itsaky.androidide.tooling.api.messages.result
  *
  * @param isSuccessful The result of the task execution.
  * @param failure The type of failure. Non-null only if [isSuccessful] is `false`.
- * @param failureMessage The message describing the failure.
  *
  * @author Akash Yadav
  */
-data class TaskExecutionResult(val isSuccessful: Boolean, val failure: Failure?, val failureMessage: String?) {
+data class TaskExecutionResult(val isSuccessful: Boolean, val failure: Failure?) {
 
   companion object {
 
@@ -34,11 +33,14 @@ data class TaskExecutionResult(val isSuccessful: Boolean, val failure: Failure?,
      * Result for a successful build.
      */
     @JvmStatic
-    val SUCCESS = TaskExecutionResult(true, null, null)
+    val SUCCESS = TaskExecutionResult(true, null)
   }
 
   enum class Failure {
     PROJECT_NOT_FOUND,
+    PROJECT_NOT_INITIALIZED,
+    PROJECT_NOT_DIRECTORY,
+    PROJECT_DIRECTORY_INACCESSIBLE,
     UNKNOWN,
     UNSUPPORTED_GRADLE_VERSION,
     UNSUPPORTED_CONFIGURATION,