diff --git a/tests/install-rust.sh b/tests/install-rust.sh
index 3698c21a50..93fa8f0c6c 100755
--- a/tests/install-rust.sh
+++ b/tests/install-rust.sh
@@ -31,6 +31,13 @@ rustup default stable
 if [[ "${RUNNER_OS:-}" == "Windows" ]]; then
   # On Windows, add Windows-native targets
   rustup target add x86_64-pc-windows-msvc --toolchain stable || true
+  # Also pre-install the Linux cross-compile targets used by cargo-lambda.
+  # If cargo-lambda has to install these on demand during parallel test runs
+  # (pytest -n 2), concurrent rustup invocations can produce a partial/corrupt
+  # target install (e.g., "can't find crate for `adler2`"). Pre-installing here
+  # avoids that race.
+  rustup target add x86_64-unknown-linux-gnu --toolchain stable
+  rustup target add aarch64-unknown-linux-gnu --toolchain stable
 else
   rustup target add x86_64-unknown-linux-gnu --toolchain stable
   rustup target add aarch64-unknown-linux-gnu --toolchain stable
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_function/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_function/main.tf
index 52baf96f91..bae31fbaac 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_function/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_function/main.tf
@@ -34,7 +34,7 @@ EOF
 resource "aws_lambda_function" "this" {
     filename = var.source_code
     handler = "app.lambda_handler"
-    runtime = "python3.9"
+    runtime = "python3.12"
     function_name = var.function_name
     role = aws_iam_role.iam_for_lambda.arn
     layers = var.layers
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_layer/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_layer/main.tf
index 67ef4fc6c5..c443f0c769 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_layer/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/modules/lambda_layer/main.tf
@@ -10,7 +10,7 @@ resource "aws_lambda_layer_version" "layer" {
   filename   = var.source_code
   layer_name = var.name
 
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
 }
 
 output "arn" {
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/root_module/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/root_module/main.tf
index ca87fbc4bf..82a13dfa2c 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/root_module/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory/root_module/main.tf
@@ -61,7 +61,7 @@ resource "aws_lambda_layer_version" "layer1" {
   count               = 1
   filename            = "${local.building_path}/${local.layer1_artifact_file_name}"
   layer_name          = "lambda_layer1"
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
   depends_on = [
     null_resource.build_layer1_version
   ]
@@ -96,7 +96,7 @@ resource "null_resource" "sam_metadata_aws_lambda_function1" {
 resource "aws_lambda_function" "function1" {
   filename      = "${local.building_path}/${local.hello_world_artifact_file_name}"
   handler       = "app.lambda_handler"
-  runtime       = "python3.9"
+  runtime       = "python3.12"
   function_name = "function1"
   timeout       = 300
   role          = aws_iam_role.iam_for_lambda.arn
@@ -174,8 +174,8 @@ module "layer7" {
   version             = "4.6.0"
   create_layer        = true
   layer_name          = "lambda_layer7"
-  compatible_runtimes = ["python3.9"]
-  runtime             = "python3.9"
+  compatible_runtimes = ["python3.12"]
+  runtime             = "python3.12"
   source_path = {
     path             = local.layer1_src_path
     prefix_in_zip    = "python"
@@ -190,6 +190,6 @@ module "function7" {
   source_path   = local.hello_world_function_src_path
   function_name = "function7"
   handler       = "app.lambda_handler"
-  runtime       = "python3.9"
+  runtime       = "python3.12"
   layers        = [module.layer7.lambda_layer_arn]
 }
\ No newline at end of file
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_function/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_function/main.tf
index 52baf96f91..bae31fbaac 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_function/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_function/main.tf
@@ -34,7 +34,7 @@ EOF
 resource "aws_lambda_function" "this" {
     filename = var.source_code
     handler = "app.lambda_handler"
-    runtime = "python3.9"
+    runtime = "python3.12"
     function_name = var.function_name
     role = aws_iam_role.iam_for_lambda.arn
     layers = var.layers
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_layer/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_layer/main.tf
index 67ef4fc6c5..c443f0c769 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_layer/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/modules/lambda_layer/main.tf
@@ -10,7 +10,7 @@ resource "aws_lambda_layer_version" "layer" {
   filename   = var.source_code
   layer_name = var.name
 
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
 }
 
 output "arn" {
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/root_module/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/root_module/main.tf
index 8b965de903..9d8ed8b112 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/root_module/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows/root_module/main.tf
@@ -61,7 +61,7 @@ resource "aws_lambda_layer_version" "layer1" {
   count               = 1
   filename            = "${local.building_path}/${local.layer1_artifact_file_name}"
   layer_name          = "lambda_layer1"
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
   depends_on = [
     null_resource.build_layer1_version
   ]
@@ -96,7 +96,7 @@ resource "null_resource" "sam_metadata_aws_lambda_function1" {
 resource "aws_lambda_function" "function1" {
   filename      = "${local.building_path}/${local.hello_world_artifact_file_name}"
   handler       = "app.lambda_handler"
-  runtime       = "python3.9"
+  runtime       = "python3.12"
   function_name = "function1"
   timeout       = 300
   role          = aws_iam_role.iam_for_lambda.arn
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_function/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_function/main.tf
index 52baf96f91..bae31fbaac 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_function/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_function/main.tf
@@ -34,7 +34,7 @@ EOF
 resource "aws_lambda_function" "this" {
     filename = var.source_code
     handler = "app.lambda_handler"
-    runtime = "python3.9"
+    runtime = "python3.12"
     function_name = var.function_name
     role = aws_iam_role.iam_for_lambda.arn
     layers = var.layers
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_layer/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_layer/main.tf
index 67ef4fc6c5..c443f0c769 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_layer/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/modules/lambda_layer/main.tf
@@ -10,7 +10,7 @@ resource "aws_lambda_layer_version" "layer" {
   filename   = var.source_code
   layer_name = var.name
 
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
 }
 
 output "arn" {
diff --git a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/root_module/main.tf b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/root_module/main.tf
index 3b49e4d5ee..2c83adc0ef 100644
--- a/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/root_module/main.tf
+++ b/tests/integration/testdata/buildcmd/terraform/application_outside_root_directory_windows_container/root_module/main.tf
@@ -61,7 +61,7 @@ resource "aws_lambda_layer_version" "layer1" {
   count               = 1
   filename            = "${local.building_path}/${local.layer1_artifact_file_name}"
   layer_name          = "lambda_layer1"
-  compatible_runtimes = ["python3.9"]
+  compatible_runtimes = ["python3.12"]
   depends_on = [
     null_resource.build_layer1_version
   ]
@@ -96,7 +96,7 @@ resource "null_resource" "sam_metadata_aws_lambda_function1" {
 resource "aws_lambda_function" "function1" {
   filename      = "${local.building_path}/${local.hello_world_artifact_file_name}"
   handler       = "app.lambda_handler"
-  runtime       = "python3.9"
+  runtime       = "python3.12"
   function_name = "function1"
   timeout       = 300
   role          = aws_iam_role.iam_for_lambda.arn
diff --git a/tests/integration/testdata/validate/multiple_files/template.json b/tests/integration/testdata/validate/multiple_files/template.json
index 4945b4ef41..0605be861c 100644
--- a/tests/integration/testdata/validate/multiple_files/template.json
+++ b/tests/integration/testdata/validate/multiple_files/template.json
@@ -8,7 +8,7 @@
       "Properties": {
         "CodeUri": "hello-world/",
         "Handler": "app.lambdaHandler",
-        "Runtime": "nodejs20.x"
+        "Runtime": "nodejs22.x"
       }
     }
   }
diff --git a/tests/integration/testdata/validate/with_build/.aws-sam/build/template.yaml b/tests/integration/testdata/validate/with_build/.aws-sam/build/template.yaml
index ccab4ba47c..796d449291 100644
--- a/tests/integration/testdata/validate/with_build/.aws-sam/build/template.yaml
+++ b/tests/integration/testdata/validate/with_build/.aws-sam/build/template.yaml
@@ -7,4 +7,4 @@ Resources:
     Properties:
       CodeUri: HelloWorldFunction
       Handler: app.lambdaHandler
-      Runtime: nodejs20.x
+      Runtime: nodejs22.x
diff --git a/tests/integration/testdata/validate/with_build/template.json b/tests/integration/testdata/validate/with_build/template.json
index 4945b4ef41..0605be861c 100644
--- a/tests/integration/testdata/validate/with_build/template.json
+++ b/tests/integration/testdata/validate/with_build/template.json
@@ -8,7 +8,7 @@
       "Properties": {
         "CodeUri": "hello-world/",
         "Handler": "app.lambdaHandler",
-        "Runtime": "nodejs20.x"
+        "Runtime": "nodejs22.x"
       }
     }
   }
diff --git a/tests/integration/validate/test_validate_command.py b/tests/integration/validate/test_validate_command.py
index 3f99fd032d..fe6942cc4c 100644
--- a/tests/integration/validate/test_validate_command.py
+++ b/tests/integration/validate/test_validate_command.py
@@ -160,6 +160,7 @@ def test_lint_template(self, relative_folder: str, expected_file: TemplateFileTy
             ("nodejs18.x",),
             ("ruby3.2",),
             ("dotnet6",),
+            ("nodejs20.x"),
         ]
     )
     def test_lint_deprecated_runtimes(self, runtime):
@@ -211,7 +212,6 @@ def test_lint_supported_runtimes(self):
             "java17",
             "java11",
             "java8.al2",
-            "nodejs20.x",
             "nodejs22.x",
             "nodejs24.x",
             "provided.al2",