diff --git a/.github/workflows/auto.yml b/.github/workflows/auto.yml
index a7249d8b..4bafb8df 100644
--- a/.github/workflows/auto.yml
+++ b/.github/workflows/auto.yml
@@ -24,9 +24,9 @@ jobs:
         persist-credentials: false
 
     - name: Setup Terraform
-      uses: hashicorp/setup-terraform@v1
+      uses: hashicorp/setup-terraform@v3
       with:
-        terraform_version: 0.14.7
+        terraform_version: 1.9.0
 
     - name: Format all .tf files recursively
       run: |
@@ -46,13 +46,13 @@ jobs:
         persist-credentials: false
 
     - name: Setup Terraform Lint
-      uses: terraform-linters/setup-tflint@ba6bb2989f94daf58a4cc6eac2c1ca7398a678bf # v3.0.0
+      uses: terraform-linters/setup-tflint@ae78205cfffec9e8d93fd2b3115c7e9d3166d4b6 # v5.0.0
       with:
-        tflint_version: v0.26.0
+        tflint_version: v0.59.1
 
     - name: Lint root module
       run: |
-        tflint --config ${{ github.workspace }}/.tflint.hcl ${{ github.workspace }}
+        tflint --config ${{ github.workspace }}/.tflint.hcl --chdir ${{ github.workspace }}
 
     - name: Lint modules directory in a loop
       run: |
@@ -60,7 +60,7 @@ jobs:
         do
           tflint \
             --config ${{ github.workspace }}/.tflint.hcl \
-            ${{ github.workspace }}/${m}
+            --chdir ${{ github.workspace }}/${m}
         done
 
     - name: Lint tests directory in a loop
@@ -69,7 +69,7 @@ jobs:
         do
           tflint \
             --config ${{ github.workspace }}/.tflint.hcl \
-            ${{ github.workspace }}/${m}
+            --chdir ${{ github.workspace }}/${m}
         done
 
     - name: Lint examples directory in a loop
@@ -78,5 +78,5 @@ jobs:
         do
           tflint \
             --config ${{ github.workspace }}/.tflint.hcl \
-            ${{ github.workspace }}/${m}
+            --chdir ${{ github.workspace }}/${m}
         done
diff --git a/.tflint.hcl b/.tflint.hcl
index b3d2baf3..1aa3ee58 100644
--- a/.tflint.hcl
+++ b/.tflint.hcl
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: MPL-2.0
 
 config {
-  module = false
+  call_module_type = "none"
   force = false
   disabled_by_default = false
 }
diff --git a/README.md b/README.md
index d5b9ee7f..7adef249 100644
--- a/README.md
+++ b/README.md
@@ -14,9 +14,9 @@ As the goal for this main module is to provide a drop-in solution for installing
 
 This module is intended to run in an AWS account with minimal preparation, however it does have the following pre-requisites:
 
-### Terraform version >= 0.14
+### Terraform version >= 1.9.0
 
-This module requires Terraform version `0.14` or greater to be installed on the running machine.
+This module requires Terraform version `1.9.0` or greater to be installed on the running machine.
 
 ### Credentials / Permissions
 
diff --git a/locals.tf b/locals.tf
index 4081f039..bf692d7d 100644
--- a/locals.tf
+++ b/locals.tf
@@ -36,7 +36,6 @@ locals {
   standard_db     = try(module.database[0], local.default_database)
 
   selected_database = (
-    var.enable_aurora && var.db_use_mtls ? error("Both enable_aurora and db_use_mtls cannot be true.") :
     var.enable_aurora ? local.aurora_database :
     var.db_use_mtls ? local.mtls_database :
     local.standard_db
diff --git a/modules/redis-sentinel/locals.tf b/modules/redis-sentinel/locals.tf
index 944bb26e..59b2e07e 100644
--- a/modules/redis-sentinel/locals.tf
+++ b/modules/redis-sentinel/locals.tf
@@ -17,7 +17,7 @@ locals {
       redis_username = local.redis_username
       redis_password = local.redis_password
     }))
-    lbname = "${aws_route53_record.sentinel.fqdn}"
+    lbname = aws_route53_record.sentinel.fqdn
     compose = var.enable_sentinel_mtls ? base64encode(templatefile(local.compose_path_tls, {
       redis_sentinel_port = var.redis_sentinel_port
       redis_port          = var.redis_port
@@ -30,7 +30,7 @@ locals {
       redis_sentinel_leader_name = var.sentinel_leader
       redis_sentinel_port        = var.redis_sentinel_port
       redis_port                 = var.redis_port
-      lbname                     = "${aws_route53_record.sentinel.fqdn}"
+      lbname                     = aws_route53_record.sentinel.fqdn
       })) : base64encode(templatefile(local.sentinel_start_script_path, {
       redis_sentinel_password    = local.sentinel_password
       redis_sentinel_username    = local.sentinel_username
diff --git a/variables.tf b/variables.tf
index 850fe3e5..e8dce4c8 100644
--- a/variables.tf
+++ b/variables.tf
@@ -268,6 +268,10 @@ variable "db_use_mtls" {
   type        = bool
   description = "Whether or not to use mutual TLS to access database. Defaults to false if no value is given."
   default     = false
+  validation {
+    condition     = !(var.db_use_mtls && var.enable_aurora)
+    error_message = "Both db_use_mtls and enable_aurora cannot be true at the same time."
+  }
 }
 
 variable "postgres_ca_certificate_secret_id" {
diff --git a/versions.tf b/versions.tf
index 17ed3f55..416a33f5 100644
--- a/versions.tf
+++ b/versions.tf
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: MPL-2.0
 
 terraform {
-  required_version = ">= 0.14"
+  required_version = ">= 1.9.0"
   required_providers {
     aws = {
       source  = "hashicorp/aws"