diff --git a/lib/controller/checks.py b/lib/controller/checks.py
index 4d0bda2e0..cff287cda 100644
--- a/lib/controller/checks.py
+++ b/lib/controller/checks.py
@@ -88,6 +88,7 @@ from lib.core.settings import IDS_WAF_CHECK_RATIO
 from lib.core.settings import IDS_WAF_CHECK_TIMEOUT
 from lib.core.settings import MAX_DIFFLIB_SEQUENCE_LENGTH
 from lib.core.settings import NON_SQLI_CHECK_PREFIX_SUFFIX_LENGTH
+from lib.core.settings import PRECONNECT_INCOMPATIBLE_SERVERS
 from lib.core.settings import SLEEP_TIME_MARKER
 from lib.core.settings import SUHOSIN_MAX_VALUE_LENGTH
 from lib.core.settings import SUPPORTED_DBMS
@@ -1554,6 +1555,10 @@ def checkConnection(suppressOutput=False):
 
         kb.errorIsNone = False
 
+        if any(_ in (kb.serverHeader or "") for _ in PRECONNECT_INCOMPATIBLE_SERVERS):
+            singleTimeWarnMessage("turning off pre-connect mechanism because of incompatible server ('%s')" % kb.serverHeader)
+            conf.disablePrecon = True
+
         if not kb.originalPage and wasLastResponseHTTPError():
             errMsg = "unable to retrieve page content"
             raise SqlmapConnectionException(errMsg)
diff --git a/lib/core/option.py b/lib/core/option.py
index 9e70fb8da..3241edf9e 100644
--- a/lib/core/option.py
+++ b/lib/core/option.py
@@ -1852,6 +1852,7 @@ def _setKnowledgeBaseAttributes(flushAll=True):
     kb.safeCharEncode = False
     kb.safeReq = AttribDict()
     kb.secondReq = None
+    kb.serverHeader = None
     kb.singleLogFlags = set()
     kb.skipSeqMatcher = False
     kb.reduceTests = None
diff --git a/lib/core/settings.py b/lib/core/settings.py
index bdac79484..f39fd3a68 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -19,7 +19,7 @@ from lib.core.enums import DBMS_DIRECTORY_NAME
 from lib.core.enums import OS
 
 # sqlmap version (<major>.<minor>.<month>.<monthly commit>)
-VERSION = "1.2.9.0"
+VERSION = "1.2.9.1"
 TYPE = "dev" if VERSION.count('.') > 2 and VERSION.split('.')[-1] != '0' else "stable"
 TYPE_COLORS = {"dev": 33, "stable": 90, "pip": 34}
 VERSION_STRING = "sqlmap/%s#%s" % ('.'.join(VERSION.split('.')[:-1]) if VERSION.count('.') > 2 and VERSION.split('.')[-1] == '0' else VERSION, TYPE)
@@ -97,6 +97,9 @@ MAX_CONSECUTIVE_CONNECTION_ERRORS = 15
 # Timeout before the pre-connection candidate is being disposed (because of high probability that the web server will reset it)
 PRECONNECT_CANDIDATE_TIMEOUT = 10
 
+# Servers known to cause issue with pre-connection mechanism (because of lack of multi-threaded support)
+PRECONNECT_INCOMPATIBLE_SERVERS = ("SimpleHTTP",)
+
 # Maximum sleep time in "Murphy" (testing) mode
 MAX_MURPHY_SLEEP_TIME = 3
 
diff --git a/lib/request/connect.py b/lib/request/connect.py
index 5a3a267d9..1bcc2c1a4 100644
--- a/lib/request/connect.py
+++ b/lib/request/connect.py
@@ -493,6 +493,7 @@ class Connect(object):
                     code = (code or conn.code) if conn.code == kb.originalCode else conn.code  # do not override redirection code (for comparison purposes)
                     responseHeaders = conn.info()
                     responseHeaders[URI_HTTP_HEADER] = conn.geturl()
+                    kb.serverHeader = responseHeaders.get(HTTP_HEADER.SERVER, kb.serverHeader)
                 else:
                     code = None
                     responseHeaders = {}
diff --git a/txt/checksum.md5 b/txt/checksum.md5
index 65e05f8f6..d37dc4a3c 100644
--- a/txt/checksum.md5
+++ b/txt/checksum.md5
@@ -24,7 +24,7 @@ b3e60ea4e18a65c48515d04aab28ff68  extra/sqlharvest/sqlharvest.py
 1e5532ede194ac9c083891c2f02bca93  extra/wafdetectify/__init__.py
 0142de525def5e3f17092dcc1ed67c95  extra/wafdetectify/wafdetectify.py
 3459c562a6abb9b4bdcc36925f751f3e  lib/controller/action.py
-7493c782345a60f6c00c9281d51a494e  lib/controller/checks.py
+2058987606ad75435c69d28cab11ef9e  lib/controller/checks.py
 c414cecdb0472c92cf50ed5b01e4438c  lib/controller/controller.py
 c7443613a0a2505b1faec931cee2a6ef  lib/controller/handler.py
 1e5532ede194ac9c083891c2f02bca93  lib/controller/__init__.py
@@ -43,14 +43,14 @@ cada93357a7321655927fc9625b3bfec  lib/core/exception.py
 1e5532ede194ac9c083891c2f02bca93  lib/core/__init__.py
 458a194764805cd8312c14ecd4be4d1e  lib/core/log.py
 7d6edc552e08c30f4f4d49fa93b746f1  lib/core/optiondict.py
-6826030069e1cd88eb87603a50b2d251  lib/core/option.py
+62fb1b8e7a82c726eb9631daac4c82e9  lib/core/option.py
 c8c386d644d57c659d74542f5f57f632  lib/core/patch.py
 6783160150b4711d02c56ee2beadffdb  lib/core/profiling.py
 6f654e1715571eff68a0f8af3d62dcf8  lib/core/readlineng.py
 0c3eef46bdbf87e29a3f95f90240d192  lib/core/replication.py
 a7db43859b61569b601b97f187dd31c5  lib/core/revision.py
 fcb74fcc9577523524659ec49e2e964b  lib/core/session.py
-bdb6b2b1b842c4f5e2874fe3a199f648  lib/core/settings.py
+153ad66f2a6789909f4a4702650397dc  lib/core/settings.py
 dd68a9d02fccb4fa1428b20e15b0db5d  lib/core/shell.py
 a7edc9250d13af36ac0108f259859c19  lib/core/subprocessng.py
 815d1cf27f0f8738d81531e73149867d  lib/core/target.py
@@ -72,7 +72,7 @@ f2af274126ce0a789027d35d367f2b9e  lib/parse/payloads.py
 30eed3a92a04ed2c29770e1b10d39dc0  lib/request/basicauthhandler.py
 2b81435f5a7519298c15c724e3194a0d  lib/request/basic.py
 859b6ad583e0ffba154f17ee179b5b89  lib/request/comparison.py
-e284905d23658b85e94a5dd37bfb80b2  lib/request/connect.py
+4ac4e1d10210bb1bc3d64a3532c5ff8b  lib/request/connect.py
 dd4598675027fae99f2e2475b05986da  lib/request/direct.py
 2044fce3f4ffa268fcfaaf63241b1e64  lib/request/dns.py
 98535d0efca5551e712fcc4b34a3f772  lib/request/httpshandler.py