How do i fix this type mismatch of columns?

Hi @Bhaumik1

It would be extremely helpful if you always provide "Diagnostic Info" from Admin > Troubleshooting.
And always include the errors you are getting also as plain text, so other people can search for it.
That's how you become a good internet citizen and a good forum user.

You either have to change the column in the database or use a Custom Column like concat([TaskID], "") and filter on that instead.