diff --git a/build.sbt b/build.sbt
index 1a8729f3a2..9a74b9c345 100644
--- a/build.sbt
+++ b/build.sbt
@@ -21,7 +21,7 @@ ThisBuild / libraryDependencySchemes +=
   "org.scala-lang.modules" %% "scala-java8-compat" % VersionScheme.Always
 
 val commonSettings = Seq(
-  scalaVersion := "2.12.20",
+  scalaVersion := "2.13.15",
   description := "grid",
   organization := "com.gu",
   version := "0.1",
@@ -75,9 +75,6 @@ val maybeBBCLib: Option[sbt.ProjectReference] = if(bbcBuildProcess) Some(bbcProj
 
 lazy val commonLib = project("common-lib").settings(
   libraryDependencies ++= Seq(
-    // FIXME - added temporarily to assist code compatible with scala 2.12 and 2.13
-    // remove ASAP after completing 2.13 upgrade!!!
-    "org.scala-lang.modules" %% "scala-collection-compat" % "2.12.0",
     "com.gu" %% "editorial-permissions-client" % "3.0.0",
     "com.gu" %% "pan-domain-auth-play_2-8" % "7.0.0",
     "com.amazonaws" % "aws-java-sdk-iam" % awsSdkVersion,
diff --git a/common-lib/src/test/scala/com/gu/mediaservice/model/FileMetadataAggregatorTest.scala b/common-lib/src/test/scala/com/gu/mediaservice/model/FileMetadataAggregatorTest.scala
index 305381d035..bbb9915ba9 100644
--- a/common-lib/src/test/scala/com/gu/mediaservice/model/FileMetadataAggregatorTest.scala
+++ b/common-lib/src/test/scala/com/gu/mediaservice/model/FileMetadataAggregatorTest.scala
@@ -153,9 +153,9 @@ class FileMetadataAggregatorTest extends AnyFlatSpec with Matchers {
       "xmpMM:History" -> JsArray(Seq(
         JsArray(Seq(
           "{'stEvt:softwareAgent':'Adobe Photoshop CC (Macintosh)'}",
+          "{'stEvt:when':'2018-02-06T16:36:48Z'}",
           "{'stEvt:action':'created'}",
           "{'stEvt:instanceID':'xmp.iid:65d63b5e-a24e-4e51-89bd-6693ce193404'}",
-          "{'stEvt:when':'2018-02-06T16:36:48Z'}",
         ).map(JsString)),
         JsArray(Seq(
           "{'stEvt:action':'saved'}",
@@ -167,9 +167,9 @@ class FileMetadataAggregatorTest extends AnyFlatSpec with Matchers {
         JsArray(Seq(
           "{'stEvt:action':'saved'}",
           "{'stEvt:when':'2019-07-04T14:12:26+01:00'}",
+          "{'stEvt:instanceID':'xmp.iid:adbc5207-3f5b-4480-9e67-ed2a1871deb9'}",
           "{'stEvt:softwareAgent':'Adobe Photoshop CC 2019 (Macintosh)'}",
           "{'stEvt:changed':'/'}",
-          "{'stEvt:instanceID':'xmp.iid:adbc5207-3f5b-4480-9e67-ed2a1871deb9'}",
         ).map(JsString)),
         JsArray(Seq(
           "{'stEvt:parameters':'from application/vnd.adobe.photoshop to image/png'}",
diff --git a/thrall/app/lib/elasticsearch/ElasticSearch.scala b/thrall/app/lib/elasticsearch/ElasticSearch.scala
index 7b395a4fc8..1d024c94d2 100644
--- a/thrall/app/lib/elasticsearch/ElasticSearch.scala
+++ b/thrall/app/lib/elasticsearch/ElasticSearch.scala
@@ -639,7 +639,7 @@ class ElasticSearch(
     val exportsParameter = JsDefined(Json.toJson(exports)).toOption.map { cs: JsValue =>  // TODO deduplicate with set collections
       cs.as[JsArray].value.map { c =>
         asNestedMap(c)
-      }
+      }.toSeq
     }.orNull
 
     val eventualUpdateResponse = migrationAwareUpdater(
@@ -673,7 +673,7 @@ class ElasticSearch(
     val collectionsParameter = JsDefined(Json.toJson(collections)).toOption.map { cs: JsValue =>
       cs.as[JsArray].value.map { c =>
         asNestedMap(c)
-      }
+      }.toSeq
     }.orNull
 
     val eventualUpdateResponse = migrationAwareUpdater(