diff --git a/MathInputCheckRestbase.php b/MathInputCheckRestbase.php
index bf17b64..0fd2bc5 100644
--- a/MathInputCheckRestbase.php
+++ b/MathInputCheckRestbase.php
@@ -38,6 +38,17 @@ class MathInputCheckRestbase extends MathInputCheck {
 		if ( isset( $e->error->message ) ){
 			if ( $e->error->message === 'Illegal TeX function' ) {
 				return $errorRenderer->getError( 'math_unknown_function', $e->error->found );
+			} elseif ( preg_match( '/Math extension/', $e->error->message ) ) {
+				$names = MathHooks::getMathNames();
+				$mode = $names['mathml'];
+				try {
+					$host = $this->restbaseInterface->getUrl( '' );
+				}
+				catch ( Exception $ignore ) {
+					$host = 'invalid';
+				}
+				$msg = $e->error->message;
+				return $errorRenderer->getError( 'math_invalidresponse', $mode, $host, $msg );
 			}
 			return $errorRenderer->getError( 'math_syntax_error' );
 		}
diff --git a/MathMathML.php b/MathMathML.php
index dff9f41..58b9900 100644
--- a/MathMathML.php
+++ b/MathMathML.php
@@ -86,7 +86,7 @@ class MathMathML extends MathRenderer {
 	 * @see MathRenderer::render()
 	*/
 	public function render( $forceReRendering = false ) {
-		if ( $this->inputType == 'tex' ) {
+		if ( $this->inputType == 'tex' && $this->mode == 'mathml' ) {
 			$tex = $this->getTex();
 			$displaystyle = false;
 			if ( $this->getMathStyle() == 'inlineDisplaystyle' ) {
diff --git a/MathRenderer.php b/MathRenderer.php
index 1fe7ba7..fa7c4c9 100644
--- a/MathRenderer.php
+++ b/MathRenderer.php
@@ -573,14 +573,16 @@ abstract class MathRenderer {
 				}
 			}
 			$checker = new MathInputCheckRestbase( $this->userInputTex );
-			if ( $checker->isValid() ) {
-				$this->setTex( $checker->getValidTex() );
-				$this->texSecure = true;
-				return true;
-			} else {
-				$this->lastError = $checker->getError();
-				return false;
+			try {
+				if ( $checker->isValid() ) {
+					$this->setTex( $checker->getValidTex() );
+					$this->texSecure = true;
+					return true;
+				}
+			} catch ( MWException $e ) {
 			}
+			$this->lastError = $checker->getError();
+			return false;
 		}
 	}
 
diff --git a/MathRestbaseInterface.php b/MathRestbaseInterface.php
index 59fc1ec..e0d5680 100644
--- a/MathRestbaseInterface.php
+++ b/MathRestbaseInterface.php
@@ -43,7 +43,7 @@ class MathRestbaseInterface {
 		$this->calculateHash();
 		$request = array(
 			'method' => 'GET',
-			'url'    => self::getUrl( "media/math/render/$type/{$this->hash}" )
+			'url'    => $this->getUrl( "media/math/render/$type/{$this->hash}" )
 		);
 		$serviceClient = $this->getServiceClient();
 		$response = $serviceClient->run( $request );
@@ -83,6 +83,9 @@ class MathRestbaseInterface {
 			if ( isset( $json->detail ) && isset( $json->detail->success ) ) {
 				$this->success = $json->detail->success;
 				$this->error = $json->detail;
+			} else {
+				$this->success = false;
+				$this->setErrorMessage( 'Math extension cannot connect to Restbase.' );
 			}
 			return false;
 		}
@@ -104,7 +107,7 @@ class MathRestbaseInterface {
 			'body'   => $post
 		);
 		$serviceClient = $this->getServiceClient();
-		$request['url'] = self::getUrl( "media/math/check/{$this->type}" );
+		$request['url'] = $this->getUrl( "media/math/check/{$this->type}" );
 		$response = $serviceClient->run( $request );
 		if ( $response['code'] === 200 ) {
 			$res = $response['body'];
@@ -156,7 +159,7 @@ class MathRestbaseInterface {
 	 * @return string
 	 * @throws MWException
 	 */
-	private static function getUrl( $path, $internal = true ) {
+	public function getUrl( $path, $internal = true ) {
 		global $wgVirtualRestConfig, $wgMathFullRestbaseURL, $wgVisualEditorFullRestbaseURL;
 		if ( $internal && isset( $wgVirtualRestConfig['modules']['restbase'] ) ) {
 			return "/mathoid/local/v1/$path";
@@ -167,8 +170,9 @@ class MathRestbaseInterface {
 		if ( $wgVisualEditorFullRestbaseURL ) {
 			return "{$wgVisualEditorFullRestbaseURL}v1/$path";
 		}
-		throw new MWException( 'Math extension can not find Restbase URL.'.
-			' Please specify $wgMathFullRestbaseURL.' );
+		$msg = 'Math extension can not find Restbase URL. Please specify $wgMathFullRestbaseURL.';
+		$this->setErrorMessage( $msg );
+		throw new MWException( $msg );
 	}
 
 	/**
@@ -190,7 +194,7 @@ class MathRestbaseInterface {
 		try {
 			$request = array(
 				'method' => 'GET',
-				'url'    => self::getUrl( '?spec' )
+				'url'    => $this->getUrl( '?spec' )
 			);
 		} catch ( Exception $e ) {
 			return false;
@@ -244,7 +248,7 @@ class MathRestbaseInterface {
 	 */
 	public function getFullSvgUrl() {
 		$this->calculateHash();
-		return self::getUrl( "media/math/render/svg/{$this->hash}", false );
+		return $this->getUrl( "media/math/render/svg/{$this->hash}", false );
 	}
 
 	/**
@@ -289,4 +293,11 @@ class MathRestbaseInterface {
 		return $this->type;
 	}
 
+	private function setErrorMessage( $msg ) {
+		$this->error = (object)array(
+				'error' =>
+						(object)array( 'message' => $msg )
+		);
+	}
+
 }
diff --git a/MathTexvc.php b/MathTexvc.php
index eec8869..fae0576 100644
--- a/MathTexvc.php
+++ b/MathTexvc.php
@@ -465,4 +465,18 @@ class MathTexvc extends MathRenderer {
 	public function setOutputHash( $hash ) {
 		$this->hash = $hash;
 	}
+
+	/**
+	 * Skip tex check for texvc rendering mode.
+	 * Checking the tex code in texvc mode just adds a dependency to the
+	 * texvccheck binary which does not improve security since the same
+	 * checks are performed by texvc anyhow. Especially given the fact that
+	 * texvccheck was derived from texvc.
+	 * @return bool
+	 */
+	public function checkTex() {
+		return true;
+	}
+
+
 }