diff --git a/launcher-implementation/src/main/scala/xsbt/boot/ConfigurationParser.scala b/launcher-implementation/src/main/scala/xsbt/boot/ConfigurationParser.scala
index 4677450..396f0b9 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/ConfigurationParser.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/ConfigurationParser.scala
@@ -204,12 +204,20 @@ class ConfigurationParser {
   def getRepositories(m: LabelMap): List[Repository.Repository] = {
     import Repository.{ Ivy, Maven, Predefined }
     val BootOnly = "bootOnly"
+    val BootOnlyZero = "bootOnlyZero"
     val MvnComp = "mavenCompatible"
     val DescriptorOptional = "descriptorOptional"
     val DontCheckConsistency = "skipConsistencyCheck"
     val AllowInsecureProtocol = "allowInsecureProtocol"
     val OptSet =
-      Set(BootOnly, MvnComp, DescriptorOptional, DontCheckConsistency, AllowInsecureProtocol)
+      Set(
+        BootOnly,
+        BootOnlyZero,
+        MvnComp,
+        DescriptorOptional,
+        DontCheckConsistency,
+        AllowInsecureProtocol
+      )
     m.toList.map {
       case (key, None)           => Predefined(key)
       case (key, Some(BootOnly)) => Predefined(key, true)
@@ -224,13 +232,14 @@ class ConfigurationParser {
         val (optionPart, patterns) = r.tail.partition(OptSet.contains(_))
         val options = (
           optionPart.contains(BootOnly),
+          optionPart.contains(BootOnlyZero),
           optionPart.contains(MvnComp),
           optionPart.contains(DescriptorOptional),
           optionPart.contains(DontCheckConsistency),
           optionPart.contains(AllowInsecureProtocol)
         )
         (patterns, options) match {
-          case (both :: Nil, (bo, mc, dso, cc, ip)) =>
+          case (both :: Nil, (bo, boz, mc, dso, cc, ip)) =>
             Ivy(
               key,
               url,
@@ -238,11 +247,12 @@ class ConfigurationParser {
               both,
               mavenCompatible = mc,
               bootOnly = bo,
+              bootOnlyZero = boz,
               descriptorOptional = dso,
               skipConsistencyCheck = cc,
               allowInsecureProtocol = ip
             )
-          case (ivy :: art :: Nil, (bo, mc, dso, cc, ip)) =>
+          case (ivy :: art :: Nil, (bo, boz, mc, dso, cc, ip)) =>
             Ivy(
               key,
               url,
@@ -250,14 +260,15 @@ class ConfigurationParser {
               art,
               mavenCompatible = mc,
               bootOnly = bo,
+              bootOnlyZero = boz,
               descriptorOptional = dso,
               skipConsistencyCheck = cc,
               allowInsecureProtocol = ip
             )
-          case (Nil, (true, false, false, cc, ip)) =>
-            Maven(key, url, bootOnly = true, allowInsecureProtocol = ip)
-          case (Nil, (false, false, false, false, ip)) =>
-            Maven(key, url, allowInsecureProtocol = ip)
+          case (Nil, (true, boz, false, false, cc, ip)) =>
+            Maven(key, url, bootOnly = true, bootOnlyZero = boz, allowInsecureProtocol = ip)
+          case (Nil, (false, boz, false, false, false, ip)) =>
+            Maven(key, url, bootOnly = false, bootOnlyZero = boz, allowInsecureProtocol = ip)
           case _ =>
             Pre.error("could not parse %s: %s".format(key, value))
         }
diff --git a/launcher-implementation/src/main/scala/xsbt/boot/CoursierUpdate.scala b/launcher-implementation/src/main/scala/xsbt/boot/CoursierUpdate.scala
index 5bbca76..e4f99a9 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/CoursierUpdate.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/CoursierUpdate.scala
@@ -69,9 +69,9 @@ class CousierUpdate(config: UpdateConfiguration) {
     if (repositories.isEmpty) Resolve.defaultRepositories
     else Nil
 
-  def apply(target: UpdateTarget, reason: String): UpdateResult = {
+  def apply(target: UpdateTarget, sbtZero: Boolean, reason: String): UpdateResult = {
     try {
-      update(target, reason)
+      update(target, sbtZero, reason)
     } catch {
       case e: Throwable =>
         e.printStackTrace(logWriter)
@@ -82,7 +82,7 @@ class CousierUpdate(config: UpdateConfiguration) {
     }
   }
 
-  private def update(target: UpdateTarget, reason: String): UpdateResult = {
+  private def update(target: UpdateTarget, sbtZero: Boolean, reason: String): UpdateResult = {
     val deps = target match {
       case u: UpdateScala =>
         val scalaVersion = getScalaVersion
@@ -154,7 +154,7 @@ class CousierUpdate(config: UpdateConfiguration) {
             case _ => Nil
           })
     }
-    update(target, deps)
+    update(target, sbtZero, deps)
   }
 
   private def detectScalaVersion(dependencySet: Set[Dependency]): Option[String] = {
@@ -176,9 +176,15 @@ class CousierUpdate(config: UpdateConfiguration) {
   /** Runs the resolve and retrieve for the given moduleID, which has had its dependencies added already. */
   private def update(
       target: UpdateTarget,
+      sbtZero: Boolean,
       deps: List[Dependency]
   ): UpdateResult = {
-    val repos = config.repositories.map(toCoursierRepository)
+    val repos = config.repositories.flatMap {
+      case repo: xsbt.boot.Repository.Repository =>
+        if (sbtZero || !repo.bootOnlyZero) Some(toCoursierRepository(repo))
+        else None
+      case repo => Some(toCoursierRepository(repo))
+    }
     val params = scalaVersion match {
       case Some(sv) if sv != "auto" =>
         ResolutionParams()
@@ -334,6 +340,8 @@ class CousierUpdate(config: UpdateConfiguration) {
             Repositories.sonatype("snapshots")
           case Jcenter =>
             Repositories.jcenter
+          case ScalaToolsReleases | ScalaToolsSnapshots =>
+            sys.error(s"unsupported repo: ${p.id}")
         }
     }
   }
diff --git a/launcher-implementation/src/main/scala/xsbt/boot/Launch.scala b/launcher-implementation/src/main/scala/xsbt/boot/Launch.scala
index 0ff537c..32fcf11 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/Launch.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/Launch.scala
@@ -233,8 +233,14 @@ class Launch private[xsbt] (
 
   def globalLock: xsbti.GlobalLock = Locks
   def ivyHome = orNull(ivyOptions.ivyHome)
-  def ivyRepositories = (repositories: List[xsbti.Repository]).toArray
-  def appRepositories = ((repositories filterNot (_.bootOnly)): List[xsbti.Repository]).toArray
+  def ivyRepositories =
+    ((repositories
+      .filterNot(_.bootOnlyZero)): List[xsbti.Repository]).toArray
+  def allRepositories = (repositories: List[xsbti.Repository]).toArray
+  def appRepositories =
+    ((repositories
+      .filterNot(_.bootOnly)
+      .filterNot(_.bootOnlyZero)): List[xsbti.Repository]).toArray
   def isOverrideRepositories: Boolean = ivyOptions.isOverrideRepositories
   def checksums = checksumsList.toArray[String]
 
diff --git a/launcher-implementation/src/main/scala/xsbt/boot/LaunchConfiguration.scala b/launcher-implementation/src/main/scala/xsbt/boot/LaunchConfiguration.scala
index 4474aa1..4429bc6 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/LaunchConfiguration.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/LaunchConfiguration.scala
@@ -211,11 +211,13 @@ object Application {
 object Repository {
   trait Repository extends xsbti.Repository {
     def bootOnly: Boolean
+    def bootOnlyZero: Boolean
   }
   final case class Maven(
       id: String,
       url: URL,
       bootOnly: Boolean = false,
+      bootOnlyZero: Boolean = false,
       allowInsecureProtocol: Boolean = false
   ) extends xsbti.MavenRepository
       with Repository
@@ -226,13 +228,17 @@ object Repository {
       artifactPattern: String,
       mavenCompatible: Boolean,
       bootOnly: Boolean = false,
+      bootOnlyZero: Boolean = false,
       descriptorOptional: Boolean = false,
       skipConsistencyCheck: Boolean = false,
       allowInsecureProtocol: Boolean = false
   ) extends xsbti.IvyRepository
       with Repository
-  final case class Predefined(id: xsbti.Predefined, bootOnly: Boolean = false)
-      extends xsbti.PredefinedRepository
+  final case class Predefined(
+      id: xsbti.Predefined,
+      bootOnly: Boolean = false,
+      bootOnlyZero: Boolean = false
+  ) extends xsbti.PredefinedRepository
       with Repository
   object Predefined {
     def apply(s: String): Predefined = new Predefined(xsbti.Predefined.toValue(s), false)
diff --git a/launcher-implementation/src/main/scala/xsbt/boot/ModuleDefinition.scala b/launcher-implementation/src/main/scala/xsbt/boot/ModuleDefinition.scala
index 83e2c42..9997bb8 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/ModuleDefinition.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/ModuleDefinition.scala
@@ -14,7 +14,11 @@ final class ModuleDefinition(
   def retrieveCorrupt(missing: Iterable[String]): Nothing =
     fail(": missing " + missing.mkString(", "))
   private def fail(extra: String) =
-    throw new xsbti.RetrieveException(versionString, "could not retrieve " + failLabel + extra)
+    throw new xsbti.RetrieveException(
+      versionString,
+      "could not retrieve " + failLabel + extra
+        + " " + configuration.repositories.mkString(", ")
+    )
   private def versionString: String = target match {
     case _: UpdateScala => configuration.getScalaVersion;
     case a: UpdateApp   => Value.get(a.id.version)
diff --git a/launcher-implementation/src/main/scala/xsbt/boot/Update.scala b/launcher-implementation/src/main/scala/xsbt/boot/Update.scala
index 28dc04a..8393609 100644
--- a/launcher-implementation/src/main/scala/xsbt/boot/Update.scala
+++ b/launcher-implementation/src/main/scala/xsbt/boot/Update.scala
@@ -116,6 +116,41 @@ final class Update(config: UpdateConfiguration) {
     if (realm != null && host != null && user != null && password != null)
       CredentialsStore.INSTANCE.addCredentials(realm, host, user, password)
   }
+
+  private[this] def setScalaVariable(settings: IvySettings, scalaVersion: Option[String]): Unit =
+    scalaVersion match { case Some(sv) => settings.setVariable("scala", sv); case None => }
+
+  // should be the same file as is used in the Ivy module
+  private lazy val ivyLockFile = new File(settings.getDefaultIvyUserDir, ".sbt.ivy.lock")
+  lazy val coursierUpdate = new CousierUpdate(config)
+  var sbtZero = false
+
+  /** The main entry point of this class for use by the Update module.  It runs Ivy */
+  def apply(target: UpdateTarget, reason: String): UpdateResult = {
+    val x = Option(System.getProperty("sbt.launcher.coursier"))
+    sbtZero = target match {
+      // https://github.com/sbt/sbt/issues/6447
+      case u: UpdateApp
+          if u.id.groupID == "org.scala-sbt" &&
+            u.id.getName == "sbt" && u.id.getVersion.startsWith("0.") =>
+        true
+      case _ => false
+    }
+    val useCousier = x match {
+      case Some("true") | Some("1") => true
+      case Some(_)                  => false
+      case None                     => !sbtZero
+    }
+    if (useCousier) coursierUpdate(target, sbtZero, reason)
+    else {
+      Message.setDefaultLogger(new SbtIvyLogger(logWriter))
+      val action = new Callable[UpdateResult] {
+        def call = lockedApply(target, reason)
+      }
+      Locks(ivyLockFile, action)
+    }
+  }
+
   private lazy val settings = {
     addCredentials()
     val settings = new IvySettings
@@ -127,8 +162,6 @@ final class Update(config: UpdateConfiguration) {
     setScalaVariable(settings, scalaVersion)
     settings
   }
-  private[this] def setScalaVariable(settings: IvySettings, scalaVersion: Option[String]): Unit =
-    scalaVersion match { case Some(sv) => settings.setVariable("scala", sv); case None => }
   private lazy val ivy = {
     val ivy = new Ivy() {
       private val loggerEngine = new SbtMessageLoggerEngine;
@@ -138,33 +171,6 @@ final class Update(config: UpdateConfiguration) {
     ivy.bind()
     ivy
   }
-  // should be the same file as is used in the Ivy module
-  private lazy val ivyLockFile = new File(settings.getDefaultIvyUserDir, ".sbt.ivy.lock")
-  lazy val coursierUpdate = new CousierUpdate(config)
-
-  /** The main entry point of this class for use by the Update module.  It runs Ivy */
-  def apply(target: UpdateTarget, reason: String): UpdateResult = {
-    val x = Option(System.getProperty("sbt.launcher.coursier"))
-    val useCousier = x match {
-      case Some("true") | Some("1") => true
-      case Some(_)                  => false
-      case None =>
-        target match {
-          // https://github.com/sbt/sbt/issues/6447
-          case u: UpdateApp
-              if u.id.groupID == "org.scala-sbt" &&
-                u.id.getName == "sbt" && u.id.getVersion.startsWith("0.") =>
-            false
-          case _ => true
-        }
-    }
-    if (useCousier) coursierUpdate(target, reason)
-    else {
-      Message.setDefaultLogger(new SbtIvyLogger(logWriter))
-      val action = new Callable[UpdateResult] { def call = lockedApply(target, reason) }
-      Locks(ivyLockFile, action)
-    }
-  }
 
   private def lockedApply(target: UpdateTarget, reason: String): UpdateResult = {
     ivy.pushContext()
@@ -449,7 +455,11 @@ final class Update(config: UpdateConfiguration) {
   }
   // exclude the local Maven repository for Scala -SNAPSHOTs
   private def includeRepo(repo: xsbti.Repository) =
-    !(Repository.isMavenLocal(repo) && isSnapshot(getScalaVersion))
+    !(Repository.isMavenLocal(repo) && isSnapshot(getScalaVersion)) &&
+      (sbtZero || (repo match {
+        case r: Repository.Repository => !r.bootOnlyZero
+        case _                        => true
+      }))
   private def isSnapshot(scalaVersion: String) = scalaVersion.endsWith(Snapshot)
   private[this] val Snapshot = "-SNAPSHOT"
   private[this] val ChangingPattern = ".*" + Snapshot
diff --git a/launcher-implementation/src/test/scala/ConfigurationParserTest.scala b/launcher-implementation/src/test/scala/ConfigurationParserTest.scala
index 779afa7..add9121 100644
--- a/launcher-implementation/src/test/scala/ConfigurationParserTest.scala
+++ b/launcher-implementation/src/test/scala/ConfigurationParserTest.scala
@@ -31,47 +31,92 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
     repoFileContains(
       """|[repositories]
          |  id: http://repo1.maven.org, bootOnly, allowInsecureProtocol""".stripMargin,
-      Repository.Maven("id", new URL("http://repo1.maven.org"), true, true)
+      Repository.Maven("id", new URL("http://repo1.maven.org"), true, false, true)
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath]""".stripMargin,
       Repository
-        .Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[orgPath]", false, false)
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[orgPath]",
+          false,
+          false,
+          false
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], mavenCompatible""".stripMargin,
       Repository
-        .Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[orgPath]", true, false)
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[orgPath]",
+          mavenCompatible = true,
+          false,
+          false
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], mavenCompatible, bootOnly""".stripMargin,
-      Repository.Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[orgPath]", true, true)
+      Repository
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[orgPath]",
+          mavenCompatible = true,
+          bootOnly = true,
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], bootOnly, mavenCompatible""".stripMargin,
-      Repository.Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[orgPath]", true, true)
+      Repository
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[orgPath]",
+          mavenCompatible = true,
+          bootOnly = true,
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], bootOnly""".stripMargin,
       Repository
-        .Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[orgPath]", false, true)
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[orgPath]",
+          mavenCompatible = false,
+          bootOnly = true,
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], [artPath]""".stripMargin,
       Repository
-        .Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[artPath]", false, false)
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[artPath]",
+          mavenCompatible = false,
+        )
     )
 
     repoFileContains(
@@ -82,10 +127,8 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
         new URL("https://repo1.maven.org"),
         "[orgPath]",
         "[artPath]",
-        false,
-        false,
-        true,
-        false
+        mavenCompatible = false,
+        descriptorOptional = true,
       )
     )
 
@@ -97,10 +140,9 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
         new URL("https://repo1.maven.org"),
         "[orgPath]",
         "[artPath]",
-        false,
-        false,
-        true,
-        true
+        mavenCompatible = false,
+        descriptorOptional = true,
+        skipConsistencyCheck = true,
       )
     )
 
@@ -112,10 +154,9 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
         new URL("https://repo1.maven.org"),
         "[orgPath]",
         "[artPath]",
-        false,
-        false,
-        true,
-        true
+        mavenCompatible = false,
+        descriptorOptional = true,
+        skipConsistencyCheck = true,
       )
     )
 
@@ -127,10 +168,10 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
         new URL("https://repo1.maven.org"),
         "[orgPath]",
         "[artPath]",
-        true,
-        true,
-        true,
-        true
+        mavenCompatible = true,
+        bootOnly = true,
+        descriptorOptional = true,
+        skipConsistencyCheck = true,
       )
     )
 
@@ -138,19 +179,53 @@ object ConfigurationParserTest extends verify.BasicTestSuite {
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], [artPath], bootOnly""".stripMargin,
       Repository
-        .Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[artPath]", false, true)
+        .Ivy(
+          "id",
+          new URL("https://repo1.maven.org"),
+          "[orgPath]",
+          "[artPath]",
+          mavenCompatible = false,
+          bootOnly = true,
+        )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], [artPath], bootOnly, mavenCompatible""".stripMargin,
-      Repository.Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[artPath]", true, true)
+      Repository.Ivy(
+        "id",
+        new URL("https://repo1.maven.org"),
+        "[orgPath]",
+        "[artPath]",
+        mavenCompatible = true,
+        bootOnly = true,
+      )
     )
 
     repoFileContains(
       """|[repositories]
                                           |  id: https://repo1.maven.org, [orgPath], [artPath], mavenCompatible, bootOnly""".stripMargin,
-      Repository.Ivy("id", new URL("https://repo1.maven.org"), "[orgPath]", "[artPath]", true, true)
+      Repository.Ivy(
+        "id",
+        new URL("https://repo1.maven.org"),
+        "[orgPath]",
+        "[artPath]",
+        mavenCompatible = true,
+        bootOnly = true,
+      )
+    )
+
+    repoFileContains(
+      """|[repositories]
+                                          |  id: https://repo1.maven.org, [orgPath], [artPath], mavenCompatible, bootOnlyZero""".stripMargin,
+      Repository.Ivy(
+        "id",
+        new URL("https://repo1.maven.org"),
+        "[orgPath]",
+        "[artPath]",
+        mavenCompatible = true,
+        bootOnlyZero = true,
+      )
     )
 
     repoFileContains(