Error: XMLHttpRequest on the main thread is deprecated

To avoid this warning, do not use:

async: false

in any of your $.ajax() calls. This is the only feature of XMLHttpRequest that's deprecated.

The default is async: true, so if you never use this option at all, your code should be safe if the feature is ever really removed (it probably won't be -- it may be removed from the standards, but I'll bet browsers will continue to support it for many years).

Another reason (In my case):

- using : async: false

- Call CountAsync() (Iqueryable):

        public virtual int Count(Expression<Func<TEntity, bool>> where)
        {
              return where == null ? _dbSet.AsQueryable().CountAsync().Result :            _dbSet.Where(where).CountAsync().Result;
        }