diff --git a/build-plugin/src/main/kotlin/AndroidExtension.kt b/build-plugin/src/main/kotlin/AndroidExtension.kt
index 81395391ec0..b0a1e6d7312 100644
--- a/build-plugin/src/main/kotlin/AndroidExtension.kt
+++ b/build-plugin/src/main/kotlin/AndroidExtension.kt
@@ -28,12 +28,6 @@ internal fun CommonExtension<*, *, *, *, *, *>.configureSharedConfig(project: Pr
         checkReleaseBuilds = System.getenv("CI_CHECK_RELEASE_BUILDS")?.toBoolean() ?: true
     }
 
-    testOptions {
-        unitTests {
-            isIncludeAndroidResources = true
-        }
-    }
-
     packaging {
         resources {
             excludes += listOf(
diff --git a/build-plugin/src/main/kotlin/thunderbird.library.android.gradle.kts b/build-plugin/src/main/kotlin/thunderbird.library.android.gradle.kts
index 75a1077b660..9e6a1a320a6 100644
--- a/build-plugin/src/main/kotlin/thunderbird.library.android.gradle.kts
+++ b/build-plugin/src/main/kotlin/thunderbird.library.android.gradle.kts
@@ -15,12 +15,6 @@ android {
     kotlinOptions {
         jvmTarget = ThunderbirdProjectConfig.Compiler.javaCompatibility.toString()
     }
-
-    testOptions {
-        unitTests {
-            isIncludeAndroidResources = true
-        }
-    }
 }
 
 kotlin {
diff --git a/core/ui/compose/common/build.gradle.kts b/core/ui/compose/common/build.gradle.kts
index c64b04956f2..931e1048718 100644
--- a/core/ui/compose/common/build.gradle.kts
+++ b/core/ui/compose/common/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.core.ui.compose.common"
     resourcePrefix = "core_ui_common_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/core/ui/compose/designsystem/build.gradle.kts b/core/ui/compose/designsystem/build.gradle.kts
index 664748c56e1..5a4b42306a4 100644
--- a/core/ui/compose/designsystem/build.gradle.kts
+++ b/core/ui/compose/designsystem/build.gradle.kts
@@ -6,6 +6,12 @@ plugins {
 android {
     namespace = "app.k9mail.core.ui.compose.designsystem"
     resourcePrefix = "designsystem_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/edit/build.gradle.kts b/feature/account/edit/build.gradle.kts
index a51deedf66d..402269e278c 100644
--- a/feature/account/edit/build.gradle.kts
+++ b/feature/account/edit/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.account.edit"
     resourcePrefix = "account_edit_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/oauth/build.gradle.kts b/feature/account/oauth/build.gradle.kts
index 168cd2abcc1..4e2e32c1ed3 100644
--- a/feature/account/oauth/build.gradle.kts
+++ b/feature/account/oauth/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.account.oauth"
     resourcePrefix = "account_oauth_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/server/settings/build.gradle.kts b/feature/account/server/settings/build.gradle.kts
index c4cb69f8e4f..3e4df59c0f3 100644
--- a/feature/account/server/settings/build.gradle.kts
+++ b/feature/account/server/settings/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.account.server.settings"
     resourcePrefix = "account_server_settings_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/server/validation/build.gradle.kts b/feature/account/server/validation/build.gradle.kts
index 8cfb84a748d..43ab82ba6dd 100644
--- a/feature/account/server/validation/build.gradle.kts
+++ b/feature/account/server/validation/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.account.server.validation"
     resourcePrefix = "account_server_validation_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/settings/impl/build.gradle.kts b/feature/account/settings/impl/build.gradle.kts
index cf5c51d77f4..80e1e92e93d 100644
--- a/feature/account/settings/impl/build.gradle.kts
+++ b/feature/account/settings/impl/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "net.thunderbird.feature.account.settings"
     resourcePrefix = "account_settings_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/account/setup/build.gradle.kts b/feature/account/setup/build.gradle.kts
index 34377b6fb12..9e20c942c21 100644
--- a/feature/account/setup/build.gradle.kts
+++ b/feature/account/setup/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.account.setup"
     resourcePrefix = "account_setup_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/funding/googleplay/build.gradle.kts b/feature/funding/googleplay/build.gradle.kts
index b461f36d2dc..d6c7c1c7b62 100644
--- a/feature/funding/googleplay/build.gradle.kts
+++ b/feature/funding/googleplay/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.funding.googleplay"
     resourcePrefix = "funding_googleplay_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/migration/qrcode/build.gradle.kts b/feature/migration/qrcode/build.gradle.kts
index 9ffa9225da1..9e340da7f9d 100644
--- a/feature/migration/qrcode/build.gradle.kts
+++ b/feature/migration/qrcode/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.migration.qrcode"
     resourcePrefix = "migration_qrcode_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/navigation/drawer/dropdown/build.gradle.kts b/feature/navigation/drawer/dropdown/build.gradle.kts
index 279a0c53e06..066c8189edc 100644
--- a/feature/navigation/drawer/dropdown/build.gradle.kts
+++ b/feature/navigation/drawer/dropdown/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "net.thunderbird.feature.navigation.drawer.dropdown"
     resourcePrefix = "navigation_drawer_dropdown_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/navigation/drawer/siderail/build.gradle.kts b/feature/navigation/drawer/siderail/build.gradle.kts
index 347d1fe96af..f1921bc0ab2 100644
--- a/feature/navigation/drawer/siderail/build.gradle.kts
+++ b/feature/navigation/drawer/siderail/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "net.thunderbird.feature.navigation.drawer.siderail"
     resourcePrefix = "navigation_drawer_siderail_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/notification/api/build.gradle.kts b/feature/notification/api/build.gradle.kts
index ac29c46ca89..feff6ad040c 100644
--- a/feature/notification/api/build.gradle.kts
+++ b/feature/notification/api/build.gradle.kts
@@ -40,6 +40,7 @@ kotlin {
 
 android {
     namespace = "net.thunderbird.feature.notification.api"
+
     testOptions {
         unitTests {
             isIncludeAndroidResources = true
diff --git a/feature/onboarding/migration/thunderbird/build.gradle.kts b/feature/onboarding/migration/thunderbird/build.gradle.kts
index 73111081034..7fdb1125e46 100644
--- a/feature/onboarding/migration/thunderbird/build.gradle.kts
+++ b/feature/onboarding/migration/thunderbird/build.gradle.kts
@@ -5,6 +5,12 @@ plugins {
 android {
     namespace = "app.k9mail.feature.onboarding.migration.thunderbird"
     resourcePrefix = "onboarding_migration_thunderbird_"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
 
 dependencies {
diff --git a/feature/widget/unread/build.gradle.kts b/feature/widget/unread/build.gradle.kts
index 14bbcb5d8fb..eb6f97ec850 100644
--- a/feature/widget/unread/build.gradle.kts
+++ b/feature/widget/unread/build.gradle.kts
@@ -16,4 +16,10 @@ dependencies {
 
 android {
     namespace = "app.k9mail.feature.widget.unread"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 260ab153373..6c209a6b7a4 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -61,7 +61,7 @@ detektPluginCompose = "0.4.27"
 fastAdapter = "5.7.0"
 forkhandlesBom = "2.23.0.0"
 glide = "4.16.0"
-gradle = "8.14.2"
+gradle = "9.1.0"
 icu4j = "77.1"
 javaDiffUtils = "4.16"
 jcipAnnotations = "1.0"
@@ -79,7 +79,7 @@ koinBom = "4.1.1"
 konsist = "0.17.3"
 kotlinBom = "2.2.20"
 # Needs to match the version used by Gradle, just check with `./gradlew --version`
-kotlinGradleBom = "2.0.21"
+kotlinGradleBom = "2.2.0"
 kotlinKsp = "2.2.20-2.0.4"
 kotlinxCoroutines = "1.10.2"
 kotlinxCollectionsImmutable = "0.4.0"
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 1b33c55baab..8bdaf60c75a 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 7705927e949..a35649f5fc2 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.1.0-all.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/gradlew b/gradlew
index 23d15a93670..adff685a034 100755
--- a/gradlew
+++ b/gradlew
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 #
-# Copyright © 2015-2021 the original authors.
+# Copyright © 2015 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -114,7 +114,6 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -172,7 +171,6 @@ fi
 # For Cygwin or MSYS, switch paths to Windows format before running java
 if "$cygwin" || "$msys" ; then
     APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
-    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
     JAVACMD=$( cygpath --unix "$JAVACMD" )
 
@@ -212,7 +210,6 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
-        -classpath "$CLASSPATH" \
         -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
diff --git a/gradlew.bat b/gradlew.bat
index db3a6ac207e..c4bdd3ab8e3 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -70,11 +70,10 @@ goto fail
 :execute
 @rem Setup the command line
 
-set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell
diff --git a/legacy/core/build.gradle.kts b/legacy/core/build.gradle.kts
index 49b290b5879..757f4c57a91 100644
--- a/legacy/core/build.gradle.kts
+++ b/legacy/core/build.gradle.kts
@@ -73,4 +73,10 @@ android {
     buildFeatures {
         buildConfig = true
     }
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
diff --git a/legacy/storage/build.gradle.kts b/legacy/storage/build.gradle.kts
index 52d9b9538c0..36fe2dbbda5 100644
--- a/legacy/storage/build.gradle.kts
+++ b/legacy/storage/build.gradle.kts
@@ -27,4 +27,10 @@ dependencies {
 
 android {
     namespace = "com.fsck.k9.storage"
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }
diff --git a/legacy/ui/legacy/build.gradle.kts b/legacy/ui/legacy/build.gradle.kts
index 909775faade..fb9dafe5b4b 100644
--- a/legacy/ui/legacy/build.gradle.kts
+++ b/legacy/ui/legacy/build.gradle.kts
@@ -96,4 +96,10 @@ android {
     buildFeatures {
         buildConfig = true
     }
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = true
+        }
+    }
 }