There are following steps for resolution this types of error.
Step 1: Open Excel
Step 2: Open the Menu in the top left
Step 3: Click on the "Excel Option" button
Step 4: Click the advanced tab on the left of the options screen
Step 5: Uncheck the box “Ignore other application that use Dynamic Data Exchange (DDE)”
Step 6: Click on Ok button and then try to open your excel files.
Step 1: Open Excel
Step 2: Open the Menu in the top left
Step 3: Click on the "Excel Option" button
Step 4: Click the advanced tab on the left of the options screen
Step 5: Uncheck the box “Ignore other application that use Dynamic Data Exchange (DDE)”
Step 6: Click on Ok button and then try to open your excel files.