diff --git a/include/mbedtls/config_adjust_legacy_crypto.h b/include/mbedtls/config_adjust_legacy_crypto.h
index a24616a..1d1b29e 100644
--- a/include/mbedtls/config_adjust_legacy_crypto.h
+++ b/include/mbedtls/config_adjust_legacy_crypto.h
@@ -24,6 +24,14 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_LEGACY_CRYPTO_H
 #define MBEDTLS_CONFIG_ADJUST_LEGACY_CRYPTO_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 /* Ideally, we'd set those as defaults in mbedtls_config.h, but
  * putting an #ifdef _WIN32 in mbedtls_config.h would confuse config.py.
  *
diff --git a/include/mbedtls/config_adjust_legacy_from_psa.h b/include/mbedtls/config_adjust_legacy_from_psa.h
index f5334f1..c8e4d03 100644
--- a/include/mbedtls/config_adjust_legacy_from_psa.h
+++ b/include/mbedtls/config_adjust_legacy_from_psa.h
@@ -18,6 +18,14 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_LEGACY_FROM_PSA_H
 #define MBEDTLS_CONFIG_ADJUST_LEGACY_FROM_PSA_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 /* Define appropriate ACCEL macros for the p256-m driver.
  * In the future, those should be generated from the drivers JSON description.
  */
diff --git a/include/mbedtls/config_adjust_psa_from_legacy.h b/include/mbedtls/config_adjust_psa_from_legacy.h
index 7c3a2d2..3495f67 100644
--- a/include/mbedtls/config_adjust_psa_from_legacy.h
+++ b/include/mbedtls/config_adjust_psa_from_legacy.h
@@ -20,6 +20,14 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_PSA_FROM_LEGACY_H
 #define MBEDTLS_CONFIG_ADJUST_PSA_FROM_LEGACY_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 /*
  * Ensure PSA_WANT_* defines are setup properly if MBEDTLS_PSA_CRYPTO_CONFIG
  * is not defined
diff --git a/include/mbedtls/config_adjust_psa_superset_legacy.h b/include/mbedtls/config_adjust_psa_superset_legacy.h
index 6ccb91b..0cbad25 100644
--- a/include/mbedtls/config_adjust_psa_superset_legacy.h
+++ b/include/mbedtls/config_adjust_psa_superset_legacy.h
@@ -19,6 +19,14 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_PSA_SUPERSET_LEGACY_H
 #define MBEDTLS_CONFIG_ADJUST_PSA_SUPERSET_LEGACY_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 /****************************************************************/
 /* Hashes that are built in are also enabled in PSA.
  * This simplifies dependency declarations especially
diff --git a/include/mbedtls/config_adjust_ssl.h b/include/mbedtls/config_adjust_ssl.h
index 4d8dc9d..8c82466 100644
--- a/include/mbedtls/config_adjust_ssl.h
+++ b/include/mbedtls/config_adjust_ssl.h
@@ -24,6 +24,14 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_SSL_H
 #define MBEDTLS_CONFIG_ADJUST_SSL_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 /* The following blocks make it easier to disable all of TLS,
  * or of TLS 1.2 or 1.3 or DTLS, without having to manually disable all
  * key exchanges, options and extensions related to them. */
diff --git a/include/mbedtls/config_adjust_x509.h b/include/mbedtls/config_adjust_x509.h
index d12f4d8..3c95ce4 100644
--- a/include/mbedtls/config_adjust_x509.h
+++ b/include/mbedtls/config_adjust_x509.h
@@ -24,4 +24,12 @@
 #ifndef MBEDTLS_CONFIG_ADJUST_X509_H
 #define MBEDTLS_CONFIG_ADJUST_X509_H
 
+#if !defined(MBEDTLS_CONFIG_FILES_READ)
+#error "Do not include mbedtls/config_adjust_*.h manually! This can lead to problems, " \
+    "up to and including runtime errors such as buffer overflows. " \
+    "If you're trying to fix a complaint from check_config.h, just remove " \
+    "it from your configuration file: since Mbed TLS 3.0, it is included " \
+    "automatically at the right time."
+#endif /* */
+
 #endif /* MBEDTLS_CONFIG_ADJUST_X509_H */