diff --git a/build.sbt b/build.sbt
index 0ad50dc68..0dd097327 100644
--- a/build.sbt
+++ b/build.sbt
@@ -459,6 +459,8 @@ lazy val commandProj = (project in file("main-command"))
     name := "Command",
     libraryDependencies ++= Seq(launcherInterface, sjsonNewScalaJson.value, templateResolverApi),
     Compile / scalacOptions += "-Ywarn-unused:-locals,-explicits,-privates",
+    // Removing -Xfatal-warnings is necessary because BasicKeys contains a Key for a deprecated class.
+    Compile / scalacOptions -= "-Xfatal-warnings",
     managedSourceDirectories in Compile +=
       baseDirectory.value / "src" / "main" / "contraband-scala",
     sourceManaged in (Compile, generateContrabands) := baseDirectory.value / "src" / "main" / "contraband-scala",
diff --git a/main-actions/src/main/scala/sbt/ForkTests.scala b/main-actions/src/main/scala/sbt/ForkTests.scala
index 87c7581b8..c2bf44ddd 100755
--- a/main-actions/src/main/scala/sbt/ForkTests.scala
+++ b/main-actions/src/main/scala/sbt/ForkTests.scala
@@ -125,8 +125,8 @@ private[sbt] object ForkTests {
         acceptorThread.start()
 
         val fullCp = classpath ++: Seq(
-          IO.classLocationFile[ForkMain],
-          IO.classLocationFile[Framework]
+          IO.classLocationPath[ForkMain].toFile,
+          IO.classLocationPath[Framework].toFile
         )
         val options = Seq(
           "-classpath",
diff --git a/main-actions/src/main/scala/sbt/compiler/Eval.scala b/main-actions/src/main/scala/sbt/compiler/Eval.scala
index 41af56520..914867a67 100644
--- a/main-actions/src/main/scala/sbt/compiler/Eval.scala
+++ b/main-actions/src/main/scala/sbt/compiler/Eval.scala
@@ -69,7 +69,7 @@ final class Eval(
     backing: Option[File]
 ) {
   def this(mkReporter: Settings => Reporter, backing: Option[File]) =
-    this(Nil, IO.classLocationFile[Product] :: Nil, mkReporter, backing)
+    this(Nil, IO.classLocationPath[Product].toFile :: Nil, mkReporter, backing)
   def this() = this(s => new ConsoleReporter(s), None)
 
   backing.foreach(IO.createDirectory)
diff --git a/main/src/main/scala/sbt/internal/parser/SbtParser.scala b/main/src/main/scala/sbt/internal/parser/SbtParser.scala
index 98952dd89..22020d30d 100644
--- a/main/src/main/scala/sbt/internal/parser/SbtParser.scala
+++ b/main/src/main/scala/sbt/internal/parser/SbtParser.scala
@@ -42,7 +42,7 @@ private[sbt] object SbtParser {
     """.stripMargin
 
   private final val defaultClasspath =
-    sbt.io.Path.makeString(sbt.io.IO.classLocationFile[Product] :: Nil)
+    sbt.io.Path.makeString(sbt.io.IO.classLocationPath[Product].toFile :: Nil)
 
   /**
    * Provides the previous error reporting functionality in
diff --git a/main/src/test/scala/BuildPathsTest.scala b/main/src/test/scala/BuildPathsTest.scala
index b81b8416a..b24c58331 100644
--- a/main/src/test/scala/BuildPathsTest.scala
+++ b/main/src/test/scala/BuildPathsTest.scala
@@ -8,7 +8,6 @@
 package sbt
 
 import org.specs2.mutable.Specification
-import sbt.BuildPaths
 
 object BuildPathsTest extends Specification {
 
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index 940c35405..1f73ef56f 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -9,7 +9,7 @@ object Dependencies {
   val baseScalaVersion = scala212
 
   // sbt modules
-  private val ioVersion = "1.2.1"
+  private val ioVersion = "1.3.0-M3"
   private val utilVersion = "1.3.0-M2"
   private val lmVersion = "1.2.1"
   private val zincVersion = "1.2.2"
diff --git a/run/src/test/scala/sbt/ForkTest.scala b/run/src/test/scala/sbt/ForkTest.scala
index 96c4aed34..eed1b4b98 100644
--- a/run/src/test/scala/sbt/ForkTest.scala
+++ b/run/src/test/scala/sbt/ForkTest.scala
@@ -31,8 +31,8 @@ object ForkTest extends Properties("Fork") {
   lazy val genRelClasspath = nonEmptyListOf(path)
 
   lazy val requiredEntries =
-    IO.classLocationFile[scala.Option[_]] ::
-      IO.classLocationFile[sbt.exit.type] ::
+    IO.classLocationPath[scala.Option[_]].toFile ::
+      IO.classLocationPath[sbt.exit.type].toFile ::
       Nil
   lazy val mainAndArgs =
     "sbt.exit" ::
diff --git a/sbt/src/sbt-test/actions/previous/test b/sbt/src/sbt-test/actions/previous/test
index 5975f711e..ebee855a7 100644
--- a/sbt/src/sbt-test/actions/previous/test
+++ b/sbt/src/sbt-test/actions/previous/test
@@ -1,5 +1,3 @@
-> debug
-
 > checkNext 1 2
 > checkNext 2 3
 > checkNext 3 5
diff --git a/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala b/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
index 8d2982153..e393864d5 100644
--- a/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
+++ b/scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
@@ -278,7 +278,7 @@ final class ScriptedTests(
       |  def setUpScripted = Command.command("setUpScripted") { (state0: State) =>
       |    val nameScriptedSetting = name.in(LocalRootProject).:=(
       |        if (name.value.startsWith("sbt_")) "$testName" else name.value)
-      |    val state1 = Project.extract(state0).append(nameScriptedSetting, state0)
+      |    val state1 = Project.extract(state0).appendWithoutSession(nameScriptedSetting, state0)
       |    "initialize" :: state1
       |  }
       |}
diff --git a/testing/src/main/scala/sbt/TestFramework.scala b/testing/src/main/scala/sbt/TestFramework.scala
index 82d6e75a5..ad8b8d91f 100644
--- a/testing/src/main/scala/sbt/TestFramework.scala
+++ b/testing/src/main/scala/sbt/TestFramework.scala
@@ -250,7 +250,7 @@ object TestFramework {
       scalaInstance: ScalaInstance,
       tempDir: File
   ): ClassLoader = {
-    val interfaceJar = IO.classLocationFile(classOf[testing.Framework])
+    val interfaceJar = IO.classLocationPath(classOf[testing.Framework]).toFile
     val interfaceFilter = (name: String) =>
       name.startsWith("org.scalatools.testing.") || name.startsWith("sbt.testing.")
     val notInterfaceFilter = (name: String) => !interfaceFilter(name)