diff --git a/ChangeLog.d/ssl-error-code-cleanup.txt b/ChangeLog.d/ssl-error-code-cleanup.txt
new file mode 100644
index 0000000..768d190
--- /dev/null
+++ b/ChangeLog.d/ssl-error-code-cleanup.txt
@@ -0,0 +1,6 @@
+API changes
+   * Remove SSL error codes `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
+     and `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH` which are never
+     returned from the public SSL API.
+   * Remove `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` and return
+     `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead.
diff --git a/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md b/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md
new file mode 100644
index 0000000..49d1a0f
--- /dev/null
+++ b/docs/3.0-migration-guide.d/ssl-error-code-cleanup.md
@@ -0,0 +1,20 @@
+Removal of some SSL error codes
+-----------------------------------------------------------------
+
+This affects users manually checking for the following error codes:
+- `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
+- `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH`
+- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE`
+
+Migration paths:
+- `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED` and `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH`
+  should never be returned from Mbed TLS, and there is no need to check for it.
+  Users should simply remove manual checks for those codes, and let the Mbed TLS
+  team know if -- contrary to the team's understanding -- there is in fact a situation
+  where one of them was ever returned.
+- `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` has been removed, and
+  `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` is returned instead if the user's own certificate
+  is too large to fit into the output buffers. Users should check for
+  `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead, and potentially compare the size of their
+  own certificate against the configured size of the output buffer to understand if
+  the error is due to an overly large certificate.
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 94b95fc..199ea3d 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -106,8 +106,10 @@
  * HKDF      5   1 (Started from top)
  * SSL       5   2 (Started from 0x5F00)
  * CIPHER    6   8 (Started from 0x6080)
- * SSL       6   24 (Started from top, plus 0x6000)
- * SSL       7   32
+ * SSL       6   23 (Started from top, plus 0x6000, gaps at
+ *                   0x6600)
+ * SSL       7   28 (Started from 0x7080, gaps at
+ *                   0x7300, 0x7500, 0x7580, 0x7800)
  *
  * Module dependent error code (5 bits 0x.00.-0x.F8.)
  */
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index b9b2e04..c9c1a66 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -67,17 +67,17 @@
 #define MBEDTLS_ERR_SSL_INVALID_MAC                       -0x7180  /**< Verification of the message MAC failed. */
 #define MBEDTLS_ERR_SSL_INVALID_RECORD                    -0x7200  /**< An invalid SSL record was received. */
 #define MBEDTLS_ERR_SSL_CONN_EOF                          -0x7280  /**< The connection indicated an EOF. */
-#define MBEDTLS_ERR_SSL_UNKNOWN_CIPHER                    -0x7300  /**< An unknown cipher was received. */
+/* NOTE: Error space gap */
 #define MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN                  -0x7380  /**< The server has no ciphersuites in common with the client. */
 #define MBEDTLS_ERR_SSL_NO_RNG                            -0x7400  /**< No RNG was provided to the SSL module. */
 #define MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE             -0x7480  /**< No client certification received from the client, but required by the authentication mode. */
-#define MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE             -0x7500  /**< Our own certificate(s) is/are too large to send in an SSL message. */
-#define MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED              -0x7580  /**< The own certificate is not set, but needed by the server. */
+/* NOTE: Error space gap */
+/* NOTE: Error space gap */
 #define MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED              -0x7600  /**< The own private key or pre-shared key is not set, but needed. */
 #define MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED                 -0x7680  /**< No CA Chain is set, but required to operate. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE                -0x7700  /**< An unexpected message was received from our peer. */
 #define MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE               -0x7780  /**< A fatal alert message was received from our peer. */
-#define MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED                -0x7800  /**< Verification of our peer failed. */
+/* NOTE: Error space gap */
 #define MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY                 -0x7880  /**< The peer notified us that the connection is going to be closed. */
 #define MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO               -0x7900  /**< Processing of the ClientHello handshake message failed. */
 #define MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO               -0x7980  /**< Processing of the ServerHello handshake message failed. */
@@ -111,7 +111,7 @@
 #define MBEDTLS_ERR_SSL_CLIENT_RECONNECT                  -0x6780  /**< The client initiated a reconnect from the same port. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_RECORD                 -0x6700  /**< Record header looks valid but is not expected. */
 #define MBEDTLS_ERR_SSL_NON_FATAL                         -0x6680  /**< The alert message received indicates a non-fatal error. */
-#define MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH               -0x6600  /**< Couldn't set the hash for verifying CertificateVerify */
+/* NOTE: Error space gap */
 #define MBEDTLS_ERR_SSL_CONTINUE_PROCESSING               -0x6580  /**< Internal-only message signaling that further message-processing should be done */
 #define MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS                 -0x6500  /**< The asynchronous operation is not completed yet. */
 #define MBEDTLS_ERR_SSL_EARLY_MESSAGE                     -0x6480  /**< Internal-only message signaling that a message arrived early. */
diff --git a/library/error.c b/library/error.c
index a176deb..3a84366 100644
--- a/library/error.c
+++ b/library/error.c
@@ -374,18 +374,12 @@
             return( "SSL - An invalid SSL record was received" );
         case -(MBEDTLS_ERR_SSL_CONN_EOF):
             return( "SSL - The connection indicated an EOF" );
-        case -(MBEDTLS_ERR_SSL_UNKNOWN_CIPHER):
-            return( "SSL - An unknown cipher was received" );
         case -(MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN):
             return( "SSL - The server has no ciphersuites in common with the client" );
         case -(MBEDTLS_ERR_SSL_NO_RNG):
             return( "SSL - No RNG was provided to the SSL module" );
         case -(MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE):
             return( "SSL - No client certification received from the client, but required by the authentication mode" );
-        case -(MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE):
-            return( "SSL - Our own certificate(s) is/are too large to send in an SSL message" );
-        case -(MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED):
-            return( "SSL - The own certificate is not set, but needed by the server" );
         case -(MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED):
             return( "SSL - The own private key or pre-shared key is not set, but needed" );
         case -(MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED):
@@ -394,8 +388,6 @@
             return( "SSL - An unexpected message was received from our peer" );
         case -(MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE):
             return( "SSL - A fatal alert message was received from our peer" );
-        case -(MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED):
-            return( "SSL - Verification of our peer failed" );
         case -(MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY):
             return( "SSL - The peer notified us that the connection is going to be closed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO):
@@ -462,8 +454,6 @@
             return( "SSL - Record header looks valid but is not expected" );
         case -(MBEDTLS_ERR_SSL_NON_FATAL):
             return( "SSL - The alert message received indicates a non-fatal error" );
-        case -(MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH):
-            return( "SSL - Couldn't set the hash for verifying CertificateVerify" );
         case -(MBEDTLS_ERR_SSL_CONTINUE_PROCESSING):
             return( "SSL - Internal-only message signaling that further message-processing should be done" );
         case -(MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS):
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index bc2f269..f147ad3 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1936,8 +1936,9 @@
     {
         if( mbedtls_ssl_own_cert( ssl ) == NULL )
         {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no certificate to send" ) );
-            return( MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED );
+            /* Should never happen because we shouldn't have picked the
+             * ciphersuite if we don't have a certificate. */
+            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
         }
     }
 #endif
@@ -1964,7 +1965,7 @@
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "certificate too large, %" MBEDTLS_PRINTF_SIZET
                                         " > %" MBEDTLS_PRINTF_SIZET,
                            i + 3 + n, (size_t) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
-            return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE );
+            return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
         }
 
         ssl->out_msg[i    ] = (unsigned char)( n >> 16 );
@@ -6973,14 +6974,14 @@
 {
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if( ssl->minor_ver != MBEDTLS_SSL_MINOR_VERSION_3 )
-        return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+        return( -1 );
 
     switch( md )
     {
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
 #if defined(MBEDTLS_MD5_C)
         case MBEDTLS_SSL_HASH_MD5:
-            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+            return( -1 );
 #endif
 #if defined(MBEDTLS_SHA1_C)
         case MBEDTLS_SSL_HASH_SHA1:
@@ -6999,7 +7000,7 @@
             break;
 #endif
         default:
-            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+            return( -1 );
     }
 
     return 0;
@@ -7007,7 +7008,7 @@
     (void) ssl;
     (void) md;
 
-    return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
+    return( -1 );
 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
 }