diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/api/LocationDescription.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/api/LocationDescription.scala
index 979548627..22052646a 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/api/LocationDescription.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/api/LocationDescription.scala
@@ -624,7 +624,8 @@ object LocationDescription extends StrictLogging {
                   objectKey
                 )
               )
-            case Some(l) if l.hasError => Left(l.getError.getMessage)
+            case Some(l) if l.hasError => return Left(l.getError.getMessage)
+            case Some(_) => Left("missing S3 credential")
             case None =>
               // Anonymous access.
               Right(S3PathLocationDescription(bucketName, None, None, None, objectKey))
@@ -668,7 +669,7 @@ object LocationDescription extends StrictLogging {
             } else {
               Left("missing Dropbox credential")
             }
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case None => Left("missing Dropbox credential")
         }
       case _ => Left(s"unsupported protocol: $protocol")
diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/MySQLPackage.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/MySQLPackage.scala
index e8afbbc36..33f85f03b 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/MySQLPackage.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/MySQLPackage.scala
@@ -150,7 +150,7 @@ class MySQLInferAndReadEntry extends SugarEntryExtension {
             new MySqlTableLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword, table)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a MySQL server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -395,7 +395,7 @@ class MySQLInferAndQueryEntry extends SugarEntryExtension {
             new MySqlServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a MySQL server")
           case None => return Left(s"unknown credential: $db")
         }
diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/OraclePackage.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/OraclePackage.scala
index cafaf081e..d9273b185 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/OraclePackage.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/OraclePackage.scala
@@ -170,7 +170,7 @@ class OracleInferAndReadEntry extends SugarEntryExtension {
             new OracleTableLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword, schema, table)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -424,7 +424,7 @@ class OracleInferAndQueryEntry extends SugarEntryExtension {
             new OracleServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/PostgreSQLPackage.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/PostgreSQLPackage.scala
index 81f6cd9e0..d75a82e00 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/PostgreSQLPackage.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/PostgreSQLPackage.scala
@@ -178,7 +178,7 @@ class PostgreSQLInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a PostgreSQL server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -434,7 +434,7 @@ class PostgreSQLInferAndQueryEntry extends SugarEntryExtension {
             new PostgresqlServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SQLServerPackage.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SQLServerPackage.scala
index 0db94f0e9..5fa5a1230 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SQLServerPackage.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SQLServerPackage.scala
@@ -179,7 +179,7 @@ class SQLServerInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -436,7 +436,7 @@ class SQLServerInferAndQueryEntry extends SugarEntryExtension {
             new SqlServerServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
diff --git a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SnowflakePackage.scala b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SnowflakePackage.scala
index a7a2dc9f3..283ef0259 100644
--- a/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SnowflakePackage.scala
+++ b/snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SnowflakePackage.scala
@@ -211,7 +211,7 @@ class SnowflakeInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a Snowflake server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -502,7 +502,7 @@ class SnowflakeInferAndQueryEntry extends SugarEntryExtension {
               l1.getParametersMap,
               programContext.settings
             )
-          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a Snowflake server")
           case None => return Left(s"unknown credential: $db")
         }