Can't run any rake command: “ERROR: 'rake/

2019-04-04 10:35发布

问题:

I'm trying to run the rake migrate:db command and I get the following error message:

ERROR: 'rake/rdoctask' is obsolete and no longer supported. Use 'rdoc/task' (available in RDoc 2.4.2+) instead.

I tried doing other rake commands, and I got the same error. How can I fix this?