diff --git a/internal/util-collection/src/main/scala/sbt/internal/util/Util.scala b/internal/util-collection/src/main/scala/sbt/internal/util/Util.scala
index 8ec3636a6..ca03ed381 100644
--- a/internal/util-collection/src/main/scala/sbt/internal/util/Util.scala
+++ b/internal/util-collection/src/main/scala/sbt/internal/util/Util.scala
@@ -54,7 +54,7 @@ object Util {
     System.getProperty("os.name").toLowerCase(Locale.ENGLISH).contains("windows")
 
   lazy val isCygwin: Boolean = {
-    val os = Option(System.getenv("OSTYPE"))
+    val os = sys.env.get("OSTYPE")
     os match {
       case Some(x) => x.toLowerCase(Locale.ENGLISH).contains("cygwin")
       case _       => false
@@ -64,7 +64,7 @@ object Util {
   lazy val isNonCygwinWindows: Boolean = isWindows && !isCygwin
   lazy val isCygwinWindows: Boolean = isWindows && isCygwin
 
-  lazy val isEmacs: Boolean = Option(System.getenv("INSIDE_EMACS")).isDefined
+  lazy val isEmacs: Boolean = sys.env.contains("INSIDE_EMACS")
 
   def nil[A]: List[A] = List.empty[A]
   def nilSeq[A]: Seq[A] = Seq.empty[A]
diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
index 7fecdf0e5..9fa61c02e 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
@@ -308,7 +308,7 @@ object Terminal {
   }
   private[sbt] lazy val isAnsiSupported: Boolean = logFormatEnabled.getOrElse(useColorDefault)
 
-  private[this] val isDumb = "dumb" == System.getenv("TERM")
+  private[this] val isDumb = Some("dumb") == sys.env.get("TERM")
   private[this] def isDumbTerminal = isDumb || System.getProperty("jline.terminal", "") == "none"
   private[this] val hasConsole = Option(java.lang.System.console).isDefined
   private[this] def useColorDefault: Boolean = {
@@ -736,22 +736,20 @@ object Terminal {
       val supershell: Boolean
   )
   private[sbt] val TERMINAL_PROPS = "SBT_TERMINAL_PROPS"
-  private val props = System.getenv(TERMINAL_PROPS) match {
-    case null => None
-    case p =>
-      p.split(",") match {
-        case Array(width, height, ansi, color, supershell) =>
-          Try(
-            new Props(
-              width.toInt,
-              height.toInt,
-              ansi.toBoolean,
-              color.toBoolean,
-              supershell.toBoolean
-            )
-          ).toOption
-        case _ => None
-      }
+  private val props = sys.env.get(TERMINAL_PROPS) flatMap { p =>
+    p.split(",") match {
+      case Array(width, height, ansi, color, supershell) =>
+        Try(
+          new Props(
+            width.toInt,
+            height.toInt,
+            ansi.toBoolean,
+            color.toBoolean,
+            supershell.toBoolean
+          )
+        ).toOption
+      case _ => None
+    }
   }
   private[sbt] def startedByRemoteClient = props.isDefined
 
diff --git a/launcher-package/integration-test/src/test/scala/ScriptTest.scala b/launcher-package/integration-test/src/test/scala/ScriptTest.scala
index 570f0b0dd..e1fe01b5f 100644
--- a/launcher-package/integration-test/src/test/scala/ScriptTest.scala
+++ b/launcher-package/integration-test/src/test/scala/ScriptTest.scala
@@ -4,7 +4,8 @@ import minitest._
 import java.io.File
 
 object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
-  lazy val isWindows: Boolean = sys.props("os.name").toLowerCase(java.util.Locale.ENGLISH).contains("windows")
+  lazy val isWindows: Boolean =
+    sys.props("os.name").toLowerCase(java.util.Locale.ENGLISH).contains("windows")
   lazy val sbtScript =
     if (isWindows) new File("target/universal/stage/bin/sbt.bat")
     else new File("target/universal/stage/bin/sbt")
@@ -12,12 +13,13 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
   private val javaBinDir = new File("integration-test", "bin").getAbsolutePath
 
   private def makeTest(
-    name: String,
-    javaOpts: String = "",
-    sbtOpts: String = "",
+      name: String,
+      javaOpts: String = "",
+      sbtOpts: String = "",
   )(args: String*)(f: List[String] => Any) = {
     test(name) {
-      val out = sbtProcessWithOpts(args: _*)(javaOpts = javaOpts, sbtOpts = sbtOpts).!!.linesIterator.toList
+      val out =
+        sbtProcessWithOpts(args: _*)(javaOpts = javaOpts, sbtOpts = sbtOpts).!!.linesIterator.toList
       f(out)
       ()
     }
@@ -26,12 +28,14 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
   def sbtProcess(args: String*) = sbtProcessWithOpts(args: _*)("", "")
   def sbtProcessWithOpts(args: String*)(javaOpts: String, sbtOpts: String) = {
     val path = sys.env("PATH")
-    sbt.internal.Process(Seq(sbtScript.getAbsolutePath) ++ args, new File("citest"),
+    sbt.internal.Process(
+      Seq(sbtScript.getAbsolutePath) ++ args,
+      new File("citest"),
       "JAVA_OPTS" -> javaOpts,
       "SBT_OPTS" -> sbtOpts,
       if (isWindows)
         "JAVACMD" -> new File(javaBinDir, "java.cmd").getAbsolutePath()
-      else 
+      else
         "PATH" -> (javaBinDir + File.pathSeparator + path)
     )
   }
@@ -48,9 +52,14 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
     assert(out.contains[String]("-Dsbt.color=false"))
   }
 
-  makeTest("sbt --no-colors in SBT_OPTS", sbtOpts = "--no-colors")("compile", "-v") { out: List[String] =>
-    if (isWindows) cancel("Test not supported on windows")
-    assert(out.contains[String]("-Dsbt.log.noformat=true"))
+  makeTest("sbt --no-colors in SBT_OPTS", sbtOpts = "--no-colors")("compile", "-v") {
+    out: List[String] =>
+      if (isWindows) cancel("Test not supported on windows")
+      assert(out.contains[String]("-Dsbt.log.noformat=true"))
+  }
+
+  makeTest("sbt --no-server")("compile", "--no-server", "-v") { out: List[String] =>
+    assert(out.contains[String]("-Dsbt.server.autostart=false"))
   }
 
   makeTest("sbt --debug-inc")("compile", "--debug-inc", "-v") { out: List[String] =>
@@ -77,33 +86,43 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
     assert(out.contains[String]("-Xmx503m"))
   }
 
-  makeTest("sbt with -mem 503, -Xmx in JAVA_OPTS", javaOpts = "-Xmx1024m")("-mem", "503", "-v") { out: List[String] =>
-    assert(out.contains[String]("-Xmx503m"))
-    assert(!out.contains[String]("-Xmx1024m"))
+  makeTest("sbt with -mem 503, -Xmx in JAVA_OPTS", javaOpts = "-Xmx1024m")("-mem", "503", "-v") {
+    out: List[String] =>
+      assert(out.contains[String]("-Xmx503m"))
+      assert(!out.contains[String]("-Xmx1024m"))
   }
 
-  makeTest("sbt with -mem 503, -Xmx in SBT_OPTS", sbtOpts = "-Xmx1024m")("-mem", "503", "-v") { out: List[String] =>
-    assert(out.contains[String]("-Xmx503m"))
-    assert(!out.contains[String]("-Xmx1024m"))
+  makeTest("sbt with -mem 503, -Xmx in SBT_OPTS", sbtOpts = "-Xmx1024m")("-mem", "503", "-v") {
+    out: List[String] =>
+      assert(out.contains[String]("-Xmx503m"))
+      assert(!out.contains[String]("-Xmx1024m"))
   }
 
-  makeTest("sbt with -mem 503, -Xss in JAVA_OPTS", javaOpts = "-Xss6m")("-mem", "503", "-v") { out: List[String] =>
-    assert(out.contains[String]("-Xmx503m"))
-    assert(!out.contains[String]("-Xss6m"))
+  makeTest("sbt with -mem 503, -Xss in JAVA_OPTS", javaOpts = "-Xss6m")("-mem", "503", "-v") {
+    out: List[String] =>
+      assert(out.contains[String]("-Xmx503m"))
+      assert(!out.contains[String]("-Xss6m"))
   }
 
-  makeTest("sbt with -mem 503, -Xss in SBT_OPTS", sbtOpts = "-Xss6m")("-mem", "503", "-v") { out: List[String] =>
-    assert(out.contains[String]("-Xmx503m"))
-    assert(!out.contains[String]("-Xss6m"))
+  makeTest("sbt with -mem 503, -Xss in SBT_OPTS", sbtOpts = "-Xss6m")("-mem", "503", "-v") {
+    out: List[String] =>
+      assert(out.contains[String]("-Xmx503m"))
+      assert(!out.contains[String]("-Xss6m"))
   }
 
-  makeTest("sbt with -Xms2048M -Xmx2048M -Xss6M in JAVA_OPTS", javaOpts = "-Xms2048M -Xmx2048M -Xss6M")("-v") { out: List[String] =>
+  makeTest(
+    "sbt with -Xms2048M -Xmx2048M -Xss6M in JAVA_OPTS",
+    javaOpts = "-Xms2048M -Xmx2048M -Xss6M"
+  )("-v") { out: List[String] =>
     assert(out.contains[String]("-Xms2048M"))
     assert(out.contains[String]("-Xmx2048M"))
     assert(out.contains[String]("-Xss6M"))
   }
 
-  makeTest("sbt with -Xms2048M -Xmx2048M -Xss6M in SBT_OPTS", sbtOpts = "-Xms2048M -Xmx2048M -Xss6M")( "-v") { out: List[String] =>
+  makeTest(
+    "sbt with -Xms2048M -Xmx2048M -Xss6M in SBT_OPTS",
+    sbtOpts = "-Xms2048M -Xmx2048M -Xss6M"
+  )("-v") { out: List[String] =>
     assert(out.contains[String]("-Xms2048M"))
     assert(out.contains[String]("-Xmx2048M"))
     assert(out.contains[String]("-Xss6M"))
@@ -125,13 +144,18 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
     assert(out.contains[String]("-XX:PermSize=128M"))
   }
 
-  makeTest("sbt with -XX:+UseG1GC -XX:+PrintGC in JAVA_OPTS", javaOpts = "-XX:+UseG1GC -XX:+PrintGC")("-v") { out: List[String] =>
+  makeTest(
+    "sbt with -XX:+UseG1GC -XX:+PrintGC in JAVA_OPTS",
+    javaOpts = "-XX:+UseG1GC -XX:+PrintGC"
+  )("-v") { out: List[String] =>
     assert(out.contains[String]("-XX:+UseG1GC"))
     assert(out.contains[String]("-XX:+PrintGC"))
     assert(!out.contains[String]("-XX:+UseG1GC=-XX:+PrintGC"))
   }
 
-  makeTest("sbt with -XX:-UseG1GC -XX:-PrintGC in SBT_OPTS", sbtOpts = "-XX:+UseG1GC -XX:+PrintGC")( "-v") { out: List[String] =>
+  makeTest("sbt with -XX:-UseG1GC -XX:-PrintGC in SBT_OPTS", sbtOpts = "-XX:+UseG1GC -XX:+PrintGC")(
+    "-v"
+  ) { out: List[String] =>
     assert(out.contains[String]("-XX:+UseG1GC"))
     assert(out.contains[String]("-XX:+PrintGC"))
     assert(!out.contains[String]("-XX:+UseG1GC=-XX:+PrintGC"))
@@ -140,7 +164,8 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
   test("sbt with -debug in SBT_OPTS appears in sbt commands") {
     if (isWindows) cancel("Test not supported on windows")
 
-    val out: List[String] = sbtProcessWithOpts("compile", "-v")(javaOpts = "", sbtOpts = "-debug").!!.linesIterator.toList
+    val out: List[String] =
+      sbtProcessWithOpts("compile", "-v")(javaOpts = "", sbtOpts = "-debug").!!.linesIterator.toList
     // Debug argument must appear in the 'commands' section (after the sbt-launch.jar argument) to work
     val sbtLaunchMatcher = """^.+sbt-launch.jar["]{0,1}$""".r
     val locationOfSbtLaunchJarArg = out.zipWithIndex.collectFirst {
@@ -155,7 +180,9 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
   }
 
   makeTest("sbt --jvm-debug <port>")("--jvm-debug", "12345", "-v") { out: List[String] =>
-    assert(out.contains[String]("-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=12345"))
+    assert(
+      out.contains[String]("-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=12345")
+    )
   }
 
   makeTest("sbt --no-share adds three system properties")("--no-share") { out: List[String] =>
@@ -171,7 +198,7 @@ object SbtScriptTest extends SimpleTestSuite with PowerAssertions {
 
   test("sbt --script-version should print sbtVersion") {
     val out = sbtProcess("--script-version").!!.trim
-    val expectedVersion = "^"+SbtRunnerTest.versionRegEx+"$"
+    val expectedVersion = "^" + SbtRunnerTest.versionRegEx + "$"
     assert(out.matches(expectedVersion))
     ()
   }
diff --git a/launcher-package/src/universal/bin/sbt.bat b/launcher-package/src/universal/bin/sbt.bat
index fb325c19a..f44af2219 100755
--- a/launcher-package/src/universal/bin/sbt.bat
+++ b/launcher-package/src/universal/bin/sbt.bat
@@ -50,6 +50,7 @@ set sbt_args_sbt_dir=
 set sbt_args_sbt_version=
 set sbt_args_mem=
 set sbt_args_client=
+set sbt_args_no_server=
 
 rem users can set SBT_OPTS via .sbtopts
 if exist .sbtopts for /F %%A in (.sbtopts) do (
@@ -205,6 +206,15 @@ if defined _no_colors_arg (
   goto args_loop
 )
 
+if "%~0" == "-no-server" set _no_server_arg=true
+if "%~0" == "--no-server" set _no_server_arg=true
+
+if defined _no_server_arg (
+  set _no_server_arg=
+  set sbt_args_no_server=1
+  goto args_loop
+)
+
 if "%~0" == "-no-global" set _no_global_arg=true
 if "%~0" == "--no-global" set _no_global_arg=true
 
@@ -646,6 +656,10 @@ if defined sbt_args_traces (
   set _SBT_OPTS=-Dsbt.traces=true !_SBT_OPTS!
 )
 
+if defined sbt_args_no_server (
+  set _SBT_OPTS=-Dsbt.io.virtual=false -Dsbt.server.autostart=false !_SBT_OPTS!
+)
+
 rem TODO: _SBT_OPTS needs to be processed as args and diffed against SBT_ARGS
 
 if !sbt_args_print_sbt_version! equ 1 (
diff --git a/main-command/src/main/scala/sbt/internal/client/NetworkClient.scala b/main-command/src/main/scala/sbt/internal/client/NetworkClient.scala
index 8141376ac..71a11e6fd 100644
--- a/main-command/src/main/scala/sbt/internal/client/NetworkClient.scala
+++ b/main-command/src/main/scala/sbt/internal/client/NetworkClient.scala
@@ -139,7 +139,7 @@ class NetworkClient(
   private val rebooting = new AtomicBoolean(false)
   private lazy val noTab = arguments.completionArguments.contains("--no-tab")
   private lazy val noStdErr = arguments.completionArguments.contains("--no-stderr") &&
-    System.getenv("SBTC_AUTO_COMPLETE") == null
+    !sys.env.contains("SBTC_AUTO_COMPLETE")
 
   private def mkSocket(file: File): (Socket, Option[String]) = ClientSocket.socket(file, useJNI)
 
diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index ec25047a0..facf6637a 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -148,6 +148,7 @@ object Defaults extends BuildCommon {
     val m = (for (a <- cp; an <- a.metadata get Keys.analysis) yield (a.data, an)).toMap
     m.get _
   }
+
   private[sbt] def globalDefaults(ss: Seq[Setting[_]]): Seq[Setting[_]] =
     Def.defaultSettings(inScope(GlobalScope)(ss))
 
@@ -229,7 +230,7 @@ object Defaults extends BuildCommon {
   private[sbt] lazy val globalIvyCore: Seq[Setting[_]] =
     Seq(
       internalConfigurationMap :== Configurations.internalMap _,
-      credentials :== Nil,
+      credentials :== SysProp.sbtCredentialsEnv.toList,
       exportJars :== false,
       trackInternalDependencies :== TrackLevel.TrackAlways,
       exportToInternal :== TrackLevel.TrackAlways,
diff --git a/main/src/main/scala/sbt/internal/Banner.scala b/main/src/main/scala/sbt/internal/Banner.scala
index 35f94bc80..b43f811ad 100644
--- a/main/src/main/scala/sbt/internal/Banner.scala
+++ b/main/src/main/scala/sbt/internal/Banner.scala
@@ -10,6 +10,15 @@ package sbt.internal
 private[sbt] object Banner {
   def apply(version: String): Option[String] =
     version match {
+      case v if v.startsWith("1.6.0") =>
+        Some(s"""
+                |Here are some highlights of this release:
+                |  - Improved JDK 17 support
+                |  - Improved Build Server Protocol (BSP) support
+                |  - Tab completion of global keys
+                |See https://eed3si9n.com/sbt-1.6.0-beta for full release notes.
+                |Hide the banner for this release by running `skipBanner`.
+                |""".stripMargin.linesIterator.mkString("\n"))
       case v if v.startsWith("1.4.0") =>
         Some(s"""
                 |Here are some highlights of this release:
diff --git a/main/src/main/scala/sbt/internal/SysProp.scala b/main/src/main/scala/sbt/internal/SysProp.scala
index c761e7f04..fbf0942b2 100644
--- a/main/src/main/scala/sbt/internal/SysProp.scala
+++ b/main/src/main/scala/sbt/internal/SysProp.scala
@@ -15,8 +15,9 @@ import scala.util.control.NonFatal
 import scala.concurrent.duration._
 import sbt.internal.util.{ Terminal => ITerminal, Util }
 import sbt.internal.util.complete.SizeParser
-import sbt.nio.Keys._
 import sbt.io.syntax._
+import sbt.librarymanagement.ivy.{ Credentials, FileCredentials }
+import sbt.nio.Keys._
 
 // See also BuildPaths.scala
 // See also LineReader.scala
@@ -216,4 +217,7 @@ object SysProp {
         .getOrElse(linuxCache)
     baseCache.getAbsoluteFile / "v1"
   }
+
+  val sbtCredentialsEnv: Option[Credentials] =
+    sys.env.get("SBT_CREDENTIALS").map(raw => new FileCredentials(new File(raw)))
 }
diff --git a/main/src/main/scala/sbt/internal/TaskProgress.scala b/main/src/main/scala/sbt/internal/TaskProgress.scala
index cf9ce2e88..65fea78fc 100644
--- a/main/src/main/scala/sbt/internal/TaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/TaskProgress.scala
@@ -70,8 +70,9 @@ private[sbt] class TaskProgress(
     pending.clear()
     scheduler.shutdownNow()
     executor.shutdownNow()
-    if (!executor.awaitTermination(1, TimeUnit.SECONDS) ||
-        !scheduler.awaitTermination(1, TimeUnit.SECONDS)) {
+    if (!executor.awaitTermination(30, TimeUnit.SECONDS) ||
+        !scheduler.awaitTermination(30, TimeUnit.SECONDS)) {
+      scala.Console.err.println("timed out closing the executor of supershell")
       throw new TimeoutException
     }
   }
diff --git a/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala b/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
index 41a35ee8e..dba366578 100644
--- a/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
+++ b/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
@@ -80,11 +80,17 @@ final class BuildServerReporterImpl(
   private lazy val exchange = StandardMain.exchange
   private val problemsByFile = mutable.Map[Path, Vector[Diagnostic]]()
 
+  // sometimes the compiler returns a fake position such as <macro>
+  // on Windows, this causes InvalidPathException (see #5994 and #6720)
+  private def toSafePath(ref: VirtualFileRef): Option[Path] =
+    if (ref.id().contains("<")) None
+    else Some(converter.toPath(ref))
+
   override def sendSuccessReport(analysis: CompileAnalysis): Unit = {
     for {
       (source, infos) <- analysis.readSourceInfos.getAllSourceInfos.asScala
+      filePath <- toSafePath(source)
     } {
-      val filePath = converter.toPath(source)
       val diagnostics = infos.getReportedProblems.toSeq.flatMap(toDiagnostic)
       val params = PublishDiagnosticsParams(
         textDocument = TextDocumentIdentifier(filePath.toUri),
@@ -98,8 +104,10 @@ final class BuildServerReporterImpl(
   }
 
   override def sendFailureReport(sources: Array[VirtualFile]): Unit = {
-    for (source <- sources) {
-      val filePath = converter.toPath(source)
+    for {
+      source <- sources
+      filePath <- toSafePath(source)
+    } {
       val diagnostics = problemsByFile.getOrElse(filePath, Vector())
       val params = PublishDiagnosticsParams(
         textDocument = TextDocumentIdentifier(filePath.toUri),
@@ -116,8 +124,8 @@ final class BuildServerReporterImpl(
     for {
       id <- problem.position.sourcePath.toOption
       diagnostic <- toDiagnostic(problem)
+      filePath <- toSafePath(VirtualFileRef.of(id))
     } {
-      val filePath = converter.toPath(VirtualFileRef.of(id))
       problemsByFile(filePath) = problemsByFile.getOrElse(filePath, Vector()) :+ diagnostic
       val params = PublishDiagnosticsParams(
         TextDocumentIdentifier(filePath.toUri),
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index aa9948bfc..34650e71a 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -12,10 +12,10 @@ object Dependencies {
     sys.env.get("BUILD_VERSION") orElse sys.props.get("sbt.build.version")
 
   // sbt modules
-  private val ioVersion = nightlyVersion.getOrElse("1.6.0-M1")
+  private val ioVersion = nightlyVersion.getOrElse("1.6.0-M2")
   private val lmVersion =
-    sys.props.get("sbt.build.lm.version").orElse(nightlyVersion).getOrElse("1.6.0-M1")
-  val zincVersion = nightlyVersion.getOrElse("1.6.0-M1")
+    sys.props.get("sbt.build.lm.version").orElse(nightlyVersion).getOrElse("1.6.0-M2")
+  val zincVersion = nightlyVersion.getOrElse("1.6.0-M2")
 
   private val sbtIO = "org.scala-sbt" %% "io" % ioVersion
 
@@ -77,7 +77,7 @@ object Dependencies {
   def addSbtZincCompile = addSbtModule(sbtZincPath, "zincCompileJVM2_12", zincCompile)
   def addSbtZincCompileCore = addSbtModule(sbtZincPath, "zincCompileCoreJVM2_12", zincCompileCore)
 
-  val lmCoursierShaded = "io.get-coursier" %% "lm-coursier-shaded" % "2.0.8"
+  val lmCoursierShaded = "io.get-coursier" %% "lm-coursier-shaded" % "2.0.9"
 
   def sjsonNew(n: String) =
     Def.setting("com.eed3si9n" %% n % "0.9.1") // contrabandSjsonNewVersion.value
diff --git a/protocol/src/main/scala/sbt/internal/bsp/BuildServerConnection.scala b/protocol/src/main/scala/sbt/internal/bsp/BuildServerConnection.scala
index dc99a4973..66ac7bdf0 100644
--- a/protocol/src/main/scala/sbt/internal/bsp/BuildServerConnection.scala
+++ b/protocol/src/main/scala/sbt/internal/bsp/BuildServerConnection.scala
@@ -61,7 +61,7 @@ object BuildServerConnection {
     // For those who use an old sbt script, the -Dsbt.script is not set
     // As a fallback we try to find the sbt script in $PATH
     val fileName = if (Properties.isWin) "sbt.bat" else "sbt"
-    val envPath = Option(System.getenv("PATH")).getOrElse("")
+    val envPath = sys.env.getOrElse("PATH", "")
     val allPaths = envPath.split(File.pathSeparator).map(Paths.get(_))
     allPaths
       .map(_.resolve(fileName))
diff --git a/sbt b/sbt
index c14c2ec32..218f45141 100755
--- a/sbt
+++ b/sbt
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 set +e
-declare builtin_sbt_version="1.5.5"
+declare builtin_sbt_version="1.6.0-RC1"
 declare -a residual_args
 declare -a java_args
 declare -a scalac_args
@@ -22,6 +22,7 @@ declare sbt_verbose=
 declare sbt_debug=
 declare build_props_sbt_version=
 declare use_sbtn=
+declare no_server=
 declare sbtn_command="$SBTN_CMD"
 declare sbtn_version="1.4.7"
 
@@ -631,6 +632,7 @@ map_args () {
            -traces|--traces) options=( "${options[@]}" "-Dsbt.traces=true" ) && shift ;;
              --supershell=*) options=( "${options[@]}" "-Dsbt.supershell=${1:13}" ) && shift ;;
               -supershell=*) options=( "${options[@]}" "-Dsbt.supershell=${1:12}" ) && shift ;;
+     -no-server|--no-server) options=( "${options[@]}" "-Dsbt.io.virtual=false" "-Dsbt.server.autostart=false" ) && shift ;;
                   --color=*) options=( "${options[@]}" "-Dsbt.color=${1:8}" ) && shift ;;
                    -color=*) options=( "${options[@]}" "-Dsbt.color=${1:7}" ) && shift ;;
        -no-share|--no-share) options=( "${options[@]}" "${noshare_opts[@]}" ) && shift ;;
diff --git a/sbt-app/src/sbt-test/run/fork/src/main/scala/ForkFail.scala b/sbt-app/src/sbt-test/run/fork/src/main/scala/ForkFail.scala
index 847230c81..a1d489232 100644
--- a/sbt-app/src/sbt-test/run/fork/src/main/scala/ForkFail.scala
+++ b/sbt-app/src/sbt-test/run/fork/src/main/scala/ForkFail.scala
@@ -1,6 +1,6 @@
 object ForkTest {
   def main(args:Array[String]): Unit = {
-		val name = Option(System.getenv("flag.name")) getOrElse("flag")
+		val name = sys.env.getOrElse("flag.name", "flag")
 		println("Name: " + name)
 		val cwd = (new java.io.File(name)).getAbsoluteFile
 		cwd.getParentFile.mkdirs()
diff --git a/sbt-app/src/sbt-test/tests/fork2/changes/Test.scala b/sbt-app/src/sbt-test/tests/fork2/changes/Test.scala
index 6706da71f..f2d45c34f 100644
--- a/sbt-app/src/sbt-test/tests/fork2/changes/Test.scala
+++ b/sbt-app/src/sbt-test/tests/fork2/changes/Test.scala
@@ -1,7 +1,7 @@
 import org.scalatest.FlatSpec
 
 class Test extends FlatSpec {
-	val v = Option(System.getenv("tests.max.value")) getOrElse Int.MaxValue
+	val v = sys.env.getOrElse("tests.max.value", Int.MaxValue)
 	"A simple equation" should "hold" in {
 		assert(Int.MaxValue == v)
 	}