Aurora Serverless alter table Error 1114 table is full

Using Aurora Serverless, when attempting to alter table mytable add column mynewcolumn decimal(10,3) after myoldcolumn I receive "ERROR 1114 (HY000): The Table 'mytable' is full". The table has hundreds of millions of rows. Normally this error results from a full partition, but since I'm using Aurora Serverless, I can't manually provision partition space. What should I do to avoid this error?