A base table can contain a maximum of 2,048 columns. Up to 32 columns can be defined with a LOB data type. See Rules and Restrictions for Large Object Data Types.
A maximum of 2,560 columns can be defined for a base table over its lifetime. Dropping columns does not affect this rule.
If new columns need to be added that would exceed this number, you must create a new table. You can use the SHOW TABLE statement and INSERT … SELECT statements to create and load the spin-off table.