sed help

I need to replace a particular char(@) with a string on the 106th line of my file.

I am using the below command
sed "106s/@/@ < ${INSTANCE_ROOT}/${INSTANCE_NAME}/wd.conf/" start_new

Its giving a problem with the special char.

Can some help me resolve this.

The same separator character you are using for sed commands appears in your string in the filepath.

Try replaceing the first part as

"106s#@#@ ......#"

or escape those "/" like so "\/"