diff --git a/superset/assets/src/SqlLab/actions/sqlLab.js b/superset/assets/src/SqlLab/actions/sqlLab.js
index 870ca9169..4ec670d82 100644
--- a/superset/assets/src/SqlLab/actions/sqlLab.js
+++ b/superset/assets/src/SqlLab/actions/sqlLab.js
@@ -603,32 +603,34 @@ export function loadQueryEditor(queryEditor) {
 }
 
 export function setTables(tableSchemas) {
-  const tables = tableSchemas.map(tableSchema => {
-    const {
-      columns,
-      selectStar,
-      primaryKey,
-      foreignKeys,
-      indexes,
-      dataPreviewQueryId,
-    } = tableSchema.description;
-    return {
-      dbId: tableSchema.database_id,
-      queryEditorId: tableSchema.tab_state_id.toString(),
-      schema: tableSchema.schema,
-      name: tableSchema.table,
-      expanded: tableSchema.expanded,
-      id: tableSchema.id,
-      dataPreviewQueryId,
-      columns,
-      selectStar,
-      primaryKey,
-      foreignKeys,
-      indexes,
-      isMetadataLoading: false,
-      isExtraMetadataLoading: false,
-    };
-  });
+  const tables = tableSchemas
+    .filter(tableSchema => tableSchema.description !== null)
+    .map(tableSchema => {
+      const {
+        columns,
+        selectStar,
+        primaryKey,
+        foreignKeys,
+        indexes,
+        dataPreviewQueryId,
+      } = tableSchema.description;
+      return {
+        dbId: tableSchema.database_id,
+        queryEditorId: tableSchema.tab_state_id.toString(),
+        schema: tableSchema.schema,
+        name: tableSchema.table,
+        expanded: tableSchema.expanded,
+        id: tableSchema.id,
+        dataPreviewQueryId,
+        columns,
+        selectStar,
+        primaryKey,
+        foreignKeys,
+        indexes,
+        isMetadataLoading: false,
+        isExtraMetadataLoading: false,
+      };
+    });
   return { type: SET_TABLES, tables };
 }
 
diff --git a/superset/assets/src/SqlLab/reducers/getInitialState.js b/superset/assets/src/SqlLab/reducers/getInitialState.js
index dbefed7db..e04f23b93 100644
--- a/superset/assets/src/SqlLab/reducers/getInitialState.js
+++ b/superset/assets/src/SqlLab/reducers/getInitialState.js
@@ -95,33 +95,35 @@ export default function getInitialState({ defaultDbId, ...restBootstrapData }) {
 
   const tables = [];
   if (activeTab) {
-    activeTab.table_schemas.forEach(tableSchema => {
-      const {
-        columns,
-        selectStar,
-        primaryKey,
-        foreignKeys,
-        indexes,
-        dataPreviewQueryId,
-      } = tableSchema.description;
-      const table = {
-        dbId: tableSchema.database_id,
-        queryEditorId: tableSchema.tab_state_id.toString(),
-        schema: tableSchema.schema,
-        name: tableSchema.table,
-        expanded: tableSchema.expanded,
-        id: tableSchema.id,
-        isMetadataLoading: false,
-        isExtraMetadataLoading: false,
-        dataPreviewQueryId,
-        columns,
-        selectStar,
-        primaryKey,
-        foreignKeys,
-        indexes,
-      };
-      tables.push(table);
-    });
+    activeTab.table_schemas
+      .filter(tableSchema => tableSchema.description !== null)
+      .forEach(tableSchema => {
+        const {
+          columns,
+          selectStar,
+          primaryKey,
+          foreignKeys,
+          indexes,
+          dataPreviewQueryId,
+        } = tableSchema.description;
+        const table = {
+          dbId: tableSchema.database_id,
+          queryEditorId: tableSchema.tab_state_id.toString(),
+          schema: tableSchema.schema,
+          name: tableSchema.table,
+          expanded: tableSchema.expanded,
+          id: tableSchema.id,
+          isMetadataLoading: false,
+          isExtraMetadataLoading: false,
+          dataPreviewQueryId,
+          columns,
+          selectStar,
+          primaryKey,
+          foreignKeys,
+          indexes,
+        };
+        tables.push(table);
+      });
   }
 
   const { databases, queries } = restBootstrapData;
diff --git a/superset/migrations/versions/89115a40e8ea_change_table_schema_description_to_long_.py b/superset/migrations/versions/89115a40e8ea_change_table_schema_description_to_long_.py
new file mode 100644
index 000000000..a1d37ab40
--- /dev/null
+++ b/superset/migrations/versions/89115a40e8ea_change_table_schema_description_to_long_.py
@@ -0,0 +1,50 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""Change table schema description to long text
+
+Revision ID: 89115a40e8ea
+Revises: 5afa9079866a
+Create Date: 2019-12-03 13:50:24.746867
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = "89115a40e8ea"
+down_revision = "5afa9079866a"
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.databases import mysql
+from sqlalchemy.dialects.mysql.base import MySQLDialect
+
+
+def upgrade():
+    bind = op.get_bind()
+    if isinstance(bind.dialect, MySQLDialect):
+        with op.batch_alter_table("table_schema") as batch_op:
+            batch_op.alter_column(
+                "description", existing_type=sa.Text, type_=mysql.LONGTEXT
+            )
+
+
+def downgrade():
+    bind = op.get_bind()
+    if isinstance(bind.dialect, MySQLDialect):
+        with op.batch_alter_table("table_schema") as batch_op:
+            batch_op.alter_column(
+                "description", existing_type=mysql.LONGTEXT, type_=sa.Text
+            )
diff --git a/superset/models/sql_lab.py b/superset/models/sql_lab.py
index 3b9789067..22291c7b5 100644
--- a/superset/models/sql_lab.py
+++ b/superset/models/sql_lab.py
@@ -259,13 +259,18 @@ class TableSchema(Model, AuditMixinNullable, ExtraJSONMixin):
     expanded = Column(Boolean, default=False)
 
     def to_dict(self):
+        try:
+            description = json.loads(self.description)
+        except json.JSONDecodeError:
+            description = None
+
         return {
             "id": self.id,
             "tab_state_id": self.tab_state_id,
             "database_id": self.database_id,
             "schema": self.schema,
             "table": self.table,
-            "description": json.loads(self.description),
+            "description": description,
             "expanded": self.expanded,
         }