I have faced this issue after migration. I did lots of analysis and found that due to blank records in the order tables.

Please follow the below steps to fix/remove blank value from the sales_order and sales_order_grid table.

• Check and remove the record from sales_order with null value on all column
• Query to find null record - SELECT * FROM sales_flat_order WHERE state IS NULL

I hope this will help you.

I have faced this issue after migration. I did lots of analysis and found that due to blank records in the order tables.

Please follow the below steps to fix/remove blank value from the sales_order and sales_order_grid table.

• Check and remove the record from sales_order with null value on all column
• Query to find null record - SELECT * FROM sales_order WHERE state IS NULL

I hope this will help you.