diff --git a/app/conf/Configuration.scala b/app/conf/Configuration.scala
index 05971f5..0fa4888 100644
--- a/app/conf/Configuration.scala
+++ b/app/conf/Configuration.scala
@@ -16,7 +16,7 @@ import play.api.{Configuration => PlayConfiguration}
 import story_packages.services.Logging
 
 import scala.language.reflectiveCalls
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 class BadConfigurationException(msg: String) extends RuntimeException(msg)
 
diff --git a/app/story_packages/metrics/CloudWatch.scala b/app/story_packages/metrics/CloudWatch.scala
index 9d358b9..03d983b 100644
--- a/app/story_packages/metrics/CloudWatch.scala
+++ b/app/story_packages/metrics/CloudWatch.scala
@@ -7,7 +7,7 @@ import com.amazonaws.services.cloudwatch.model._
 import conf.ApplicationConfiguration
 import story_packages.services.Logging
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 class CloudWatch(config: ApplicationConfiguration) extends Logging {
 
diff --git a/app/story_packages/metrics/FrontendMetrics.scala b/app/story_packages/metrics/FrontendMetrics.scala
index 9c9be9f..93c7deb 100644
--- a/app/story_packages/metrics/FrontendMetrics.scala
+++ b/app/story_packages/metrics/FrontendMetrics.scala
@@ -26,7 +26,7 @@ case class FrontendStatisticSet(metric: FrontendMetric, datapoints: List[DataPoi
   lazy val sampleCount: Double = datapoints.size
   lazy val maximum: Double = Try(datapoints.maxBy(_.value).value).getOrElse(0L).toDouble
   lazy val minimum: Double = Try(datapoints.minBy(_.value).value).getOrElse(0L).toDouble
-  lazy val sum: Double = datapoints.map(_.value).sum
+  lazy val sum: Double = datapoints.map(_.value).sum.toDouble
   lazy val average: Double =
     Try(sum / sampleCount).toOption.getOrElse(0L)
 
diff --git a/app/story_packages/metrics/metrics.scala b/app/story_packages/metrics/metrics.scala
index 96fe76e..b896148 100644
--- a/app/story_packages/metrics/metrics.scala
+++ b/app/story_packages/metrics/metrics.scala
@@ -11,6 +11,7 @@ import story_packages.services.Logging
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.duration._
 import scala.jdk.CollectionConverters._
+import scala.collection.mutable.Buffer
 
 object SystemMetrics {
 
@@ -22,17 +23,17 @@ object SystemMetrics {
 
     def gcCount: Double = {
       val totalGcCount = bean.getCollectionCount
-      totalGcCount - lastGcCount.getAndSet(totalGcCount)
+      (totalGcCount - lastGcCount.getAndSet(totalGcCount)).toDouble
     }
 
     def gcTime: Double = {
       val totalGcTime = bean.getCollectionTime
-      totalGcTime - lastGcTime.getAndSet(totalGcTime)
+      (totalGcTime - lastGcTime.getAndSet(totalGcTime)).toDouble
     }
   }
 
 
-  lazy val garbageCollectors: Seq[GcRateMetric] = ManagementFactory.getGarbageCollectorMXBeans.asScala.map(new GcRateMetric(_))
+  lazy val garbageCollectors: Seq[GcRateMetric] = ManagementFactory.getGarbageCollectorMXBeans.asScala.map(new GcRateMetric(_)).toSeq
 
 
   // divide by 1048576 to convert bytes to MB
diff --git a/app/story_packages/services/Database.scala b/app/story_packages/services/Database.scala
index fdae3a0..310f357 100644
--- a/app/story_packages/services/Database.scala
+++ b/app/story_packages/services/Database.scala
@@ -14,7 +14,7 @@ import conf.ApplicationConfiguration
 import story_packages.updates.ReindexPage
 import story_packages.util.Identity._
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 import scala.concurrent.Future
 import scala.util.{Failure, Success, Try}
 
diff --git a/app/story_packages/services/DynamoReindexJobs.scala b/app/story_packages/services/DynamoReindexJobs.scala
index 4bbd0bb..48a1766 100644
--- a/app/story_packages/services/DynamoReindexJobs.scala
+++ b/app/story_packages/services/DynamoReindexJobs.scala
@@ -9,7 +9,7 @@ import story_packages.metrics.ReindexMetrics
 import conf.ApplicationConfiguration
 import story_packages.updates._
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 class DynamoReindexJobs(config: ApplicationConfiguration) extends Logging {
   private lazy val client =
diff --git a/app/story_packages/updates/AuditingUpdates.scala b/app/story_packages/updates/AuditingUpdates.scala
index 0ffe2d3..eafb7dc 100644
--- a/app/story_packages/updates/AuditingUpdates.scala
+++ b/app/story_packages/updates/AuditingUpdates.scala
@@ -5,7 +5,7 @@ import play.api.libs.json.Json
 import conf.ApplicationConfiguration
 import story_packages.services.Logging
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 
 class AuditingUpdates(config: ApplicationConfiguration) extends Logging {
 
diff --git a/app/story_packages/util/ContentUpgrade.scala b/app/story_packages/util/ContentUpgrade.scala
index 7b23951..fc23d43 100644
--- a/app/story_packages/util/ContentUpgrade.scala
+++ b/app/story_packages/util/ContentUpgrade.scala
@@ -46,8 +46,8 @@ object ContentUpgrade {
   def upgradeItem(json: JValue): JValue = {
     Try({
       val jsonString = JsonMethods.compact(JsonMethods.render(json))
-      val maybeParsedJson: Option[Json] = parser.parse(jsonString).right.toOption
-      val maybeCapiContent: Option[Content] = maybeParsedJson.flatMap(json => json.as[Content].right.toOption)
+      val maybeParsedJson: Option[Json] = parser.parse(jsonString).toOption
+      val maybeCapiContent: Option[Content] = maybeParsedJson.flatMap(json => json.as[Content].toOption)
 
       (json, maybeCapiContent) match {
         case (jsObject: JObject, Some(content)) =>
diff --git a/app/story_packages/util/Enumerators.scala b/app/story_packages/util/Enumerators.scala
deleted file mode 100644
index 1951d1e..0000000
--- a/app/story_packages/util/Enumerators.scala
+++ /dev/null
@@ -1,14 +0,0 @@
-package story_packages.util
-
-import play.api.libs.iteratee.Enumerator
-
-import scala.concurrent.ExecutionContext.Implicits.global
-import scala.concurrent.Future
-
-object Enumerators {
-  /** Sequentially enumerate the results of applying f to each element of as */
-  def enumerate[A, B](as: Seq[A])(f: A => Future[B]) = Enumerator.unfoldM(as) {
-    case first :: rest => f(first) map { b => Some(rest -> b) }
-    case Nil => Future.successful(None)
-  }
-}
diff --git a/app/story_packages/util/SanitizeInput.scala b/app/story_packages/util/SanitizeInput.scala
index 93cb461..af8fb17 100644
--- a/app/story_packages/util/SanitizeInput.scala
+++ b/app/story_packages/util/SanitizeInput.scala
@@ -10,7 +10,7 @@ object SanitizeInput {
   def fromString(s: String) = sanitizeRegex.replaceAllIn(s, "")
 
   def fromConfigSeo(config: ConfigJson): ConfigJson = {
-    config.copy(fronts = config.fronts.mapValues(sanitizeSeoInputFromFront))
+    config.copy(fronts = config.fronts.view.mapValues(sanitizeSeoInputFromFront).toMap)
   }
 
   private def sanitizeSeoInputFromFront(front: FrontJson): FrontJson = front.copy(
diff --git a/build.sbt b/build.sbt
index c660a93..4ec6e12 100644
--- a/build.sbt
+++ b/build.sbt
@@ -10,7 +10,7 @@ packageSummary := "Story packages"
 
 packageDescription := "Guardian story packages editor"
 
-scalaVersion := "2.12.16"
+scalaVersion := "2.13.14"
 
 import sbt.Resolver
 
@@ -28,7 +28,7 @@ Universal / javaOptions ++= Seq(
     s"-J-Xloggc:/var/log/${packageName.value}/gc.log"
 )
 
-scalacOptions := Seq("-unchecked", "-deprecation", "-target:jvm-1.8",
+scalacOptions := Seq("-unchecked", "-deprecation", "-release:8",
       "-Xcheckinit", "-encoding", "utf8", "-feature", "-Xfatal-warnings")
 
 Compile / doc / sources := Seq.empty
@@ -75,12 +75,11 @@ libraryDependencies ++= jacksonOverrides ++  Seq(
     "com.gu" %% "fapi-client-play28" % "4.0.4",
     "com.gu" %% "pan-domain-auth-play_2-8" % "4.0.0",
     "com.gu" %% "story-packages-model" % "2.2.0",
-    "com.gu" %% "thrift-serializer" % "4.0.0",
+    "com.gu" %% "thrift-serializer" % "4.0.2",
     "org.json4s" %% "json4s-native" % json4sVersion,
     "org.json4s" %% "json4s-jackson" % json4sVersion,
     "net.logstash.logback" % "logstash-logback-encoder" % "7.2",
     "com.typesafe.play" %% "play-json" % "2.9.4",
-    "com.typesafe.play" %% "play-iteratees" % "2.6.1",
     "org.julienrf" %% "play-json-derived-codecs" % "10.1.0",
     "org.scalatest" %% "scalatest" % "3.2.15" % "test"
 )
diff --git a/conf/routes b/conf/routes
index 7075da7..b731f98 100644
--- a/conf/routes
+++ b/conf/routes
@@ -23,7 +23,7 @@ GET         /editorial                               controllers.ViewsController
 GET         /training                                controllers.ViewsController.collectionEditor()
 
 GET         /collection/*collectionId                controllers.FaciaToolController.getCollection(collectionId)
-POST        /edits                                   controllers.FaciaToolController.collectionEdits
+POST        /edits                                   controllers.FaciaToolController.collectionEdits()
 GET         /defaults                                controllers.DefaultsController.configuration()
 
 GET         /story-package/*id                       controllers.StoryPackagesController.getPackage(id)
diff --git a/test/package.scala b/test/package.scala
index 4da92de..1c7e99a 100644
--- a/test/package.scala
+++ b/test/package.scala
@@ -4,6 +4,5 @@ import org.scalatest.Suites
 
 class FaciaToolTestSuite extends Suites (
   new story_packages.metrics.DurationMetricTest,
-  new story_packages.util.EnumeratorsTest,
   new story_packages.util.RichFutureTest,
   new story_packages.util.SanitizeInputTest) {}
diff --git a/test/story_packages/util/EnumeratorsTest.scala b/test/story_packages/util/EnumeratorsTest.scala
deleted file mode 100644
index d3a1626..0000000
--- a/test/story_packages/util/EnumeratorsTest.scala
+++ /dev/null
@@ -1,26 +0,0 @@
-package story_packages.util
-
-import org.scalatest.concurrent.ScalaFutures
-import org.scalatest.flatspec.AnyFlatSpec
-import org.scalatest.matchers.should.Matchers
-import play.api.libs.iteratee.Iteratee
-import story_packages.util.Enumerators._
-
-import scala.concurrent.ExecutionContext.Implicits.global
-import scala.concurrent.Future
-
-class EnumeratorsTest extends AnyFlatSpec with Matchers with ScalaFutures {
-  "enumerate" should "simply enumerate the list if the function applied lifts the value into a Future" in {
-    enumerate(List(1, 2, 3))(Future.successful).run(Iteratee.getChunks).futureValue should equal(List(
-      1, 2, 3
-    ))
-  }
-
-  it should "transform the enumerator with the given function" in {
-    enumerate(List(1, 2, 3)) { n =>
-      Future {
-        n * n
-      }
-    }.run(Iteratee.getChunks).futureValue should equal(List(1, 4, 9))
-  }
-}