diff --git a/.travis.yml b/.travis.yml
index 404c9a2315..2f8681ede5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -159,6 +159,7 @@ jobs:
 
     - stage: "Documentation"
       name: "Build API docs"
+      before_install: phpenv config-rm xdebug.ini
       before_script: skip
       after_script: skip
       after_success: skip
@@ -182,6 +183,7 @@ jobs:
         - TESTSUITE_SELENIUM_BROWSER=chrome
         - TESTSUITE_USER=root
         - TESTSUITE_URL=http://127.0.0.1:8000
+      before_install: phpenv config-rm xdebug.ini
       install:
         - ./test/install-browserstack
         - composer install --no-interaction
diff --git a/libraries/classes/Charsets.php b/libraries/classes/Charsets.php
index 475e754fb5..740ab09e76 100644
--- a/libraries/classes/Charsets.php
+++ b/libraries/classes/Charsets.php
@@ -155,6 +155,9 @@ class Charsets
         }
         self::loadCharsets($dbi, $disableIs);
         $serverCharset = $dbi->getVariable('character_set_server');
+        if (! is_string($serverCharset)) {// MySQL 5.7.8 fallback, issue #15614
+            $serverCharset = $dbi->fetchValue("SELECT @@character_set_server;");
+        }
         self::$serverCharset = self::$charsets[$serverCharset];
         return self::$serverCharset;
     }