diff --git a/.appveyor.yml b/.appveyor.yml
index e536a561ff..a4fac799b2 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -15,10 +15,10 @@ environment:
     php: 7.0
   - db: mssql
     db_version: sql2016
-    php: 7.0
-  - db: mssql
-    db_version: sql2017
-    php: 7.1
+    php: 7.1.12
+#  - db: mssql
+#    db_version: sql2017
+#    php: 7.1
 #  - db: mariadb
 #    php: 7.1
 #  - db: mysqli
@@ -40,10 +40,10 @@ before_test:
   - ps: |
       Set-Service wuauserv -StartupType Manual
       cinst -y php --version ((choco search php --exact --all-versions -r | select-string -pattern $env:php | sort { [version]($_ -split '\|' | select -last 1) } -Descending | Select-Object -first 1) -replace '[php|]','')
-      Get-ChildItem -Path "c:\tools\php$($env:php -replace '[.]','')" -Recurse |
+      Get-ChildItem -Path "c:\tools\php$($env:php -replace '([0-9])[.]([0-9])[.]?([0-9]+)?','$1$2')" -Recurse |
           Move-Item -destination "c:\tools\php"
       cd c:\tools\php
-      cat php.ini-production | %{$_ -replace "memory_limit = 128M","memory_limit = 1024M"} | Out-File -Encoding "Default" php.ini
+      cat php.ini-development | %{$_ -replace "memory_limit = 128M","memory_limit = 1024M"} | Out-File -Encoding "Default" php.ini
       Add-Content php.ini "`n date.timezone=UTC"
       Add-Content php.ini "`n display_errors=On"
       Add-Content php.ini "`n extension_dir=ext"
@@ -64,10 +64,10 @@ before_test:
       if ($env:db -eq "mssql") {
         cd c:\tools\php\ext
         $DLLVersion = "4.1.6.1"
-        appveyor DownloadFile http://windows.php.net/downloads/pecl/releases/sqlsrv/$($:DLLVersion)/php_sqlsrv-$($DLLVersion)-$($env:php)-nts-vc14-x64.zip
-        7z x -y php_sqlsrv-$($DLLVersion)-$($env:php)-nts-vc14-x64.zip > $null
-        appveyor-retry appveyor DownloadFile http://windows.php.net/downloads/pecl/releases/pdo_sqlsrv/$($DLLVersion)/php_pdo_sqlsrv-$($DLLVersion)-$($env:php)-nts-vc14-x64.zip
-        7z x -y php_pdo_sqlsrv-$($DLLVersion)-$($env:php)-nts-vc14-x64.zip > $null
+        appveyor DownloadFile http://windows.php.net/downloads/pecl/releases/sqlsrv/$($:DLLVersion)/php_sqlsrv-$($DLLVersion)-$($env:php -replace '([0-9])[.]([0-9])[.]?([0-9]+)?','$1.$2')-nts-vc14-x64.zip
+        7z x -y php_sqlsrv-$($DLLVersion)-$($env:php -replace '([0-9])[.]([0-9])[.]?([0-9]+)?','$1.$2')-nts-vc14-x64.zip > $null
+        appveyor-retry appveyor DownloadFile http://windows.php.net/downloads/pecl/releases/pdo_sqlsrv/$($DLLVersion)/php_pdo_sqlsrv-$($DLLVersion)-$($env:php -replace '([0-9])[.]([0-9])[.]?([0-9]+)?','$1.$2')-nts-vc14-x64.zip
+        7z x -y php_pdo_sqlsrv-$($DLLVersion)-$($env:php -replace '([0-9])[.]([0-9])[.]?([0-9]+)?','$1.$2')-nts-vc14-x64.zip > $null
         Remove-Item c:\tools\php\* -include .zip
         cd c:\tools\php
         Add-Content php.ini "`nextension=php_sqlsrv.dll"
@@ -114,6 +114,10 @@ before_test:
       # Install PhantomJS
       cinst -y phantomjs
       Start-Process "phantomjs" "--webdriver=8910" | Out-Null
+  - ps: |
+      cd c:\projects\phpbb\phpBB
+      (Get-Content c:\projects\phpbb\phpBB\web.config).replace("<configuration>", "<configuration>`n`t<system.web>`n`t`t<customErrors mode=`"Off`"/>`n`t</system.web>") | Set-Content c:\projects\phpbb\phpBB\web.config
+      (Get-Content c:\projects\phpbb\phpBB\web.config).replace("`t</system.webServer>", "`t`t<httpErrors errorMode=`"Detailed`" />`n`t</system.webServer>") | Set-Content c:\projects\phpbb\phpBB\web.config
   - cd c:\projects\phpbb\phpBB
   - php ..\composer.phar install
   - choco install -y urlrewrite
diff --git a/tests/test_framework/phpbb_functional_test_case.php b/tests/test_framework/phpbb_functional_test_case.php
index 2be16c7198..e1daa4558a 100644
--- a/tests/test_framework/phpbb_functional_test_case.php
+++ b/tests/test_framework/phpbb_functional_test_case.php
@@ -911,10 +911,15 @@ class phpbb_functional_test_case extends phpbb_test_case
 	* status code. This assertion tries to catch that.
 	*
 	* @param int $status_code	Expected status code
-	* @return null
+	* @return void
 	*/
 	static public function assert_response_status_code($status_code = 200)
 	{
+		if ($status_code != self::$client->getResponse()->getStatus() &&
+			preg_match('/^5[0-9]{2}/', self::$client->getResponse()->getStatus()))
+		{
+			self::fail("Encountered unexpected server error:\n" . self::$client->getResponse()->getContent());
+		}
 		self::assertEquals($status_code, self::$client->getResponse()->getStatus(), 'HTTP status code does not match');
 	}