Cannot add column to existing table. Timeout expired

Sometime when we try to add a column to a large table, an error comes "Timeout expired". We can avoid this error by applying any of the method below:

Open SQL Server Managerment Studio > Goto Tools Menu > Option > Under Option Dialogue Choose Designers > Table and Database Designers

Uncheck  the option :“Override connection string time-out value for table designer update”

Open SQL Server Managerment Studio > Goto Tools Menu > Option > Under Option Dialogue Choose Designers > Table and Database Designers

Change“Transaction time-out after:” with high value

We can create Script of Table changes and Run It as Query. See under pic to generate query for Table changes