Due to too many failed logins, I have been blocked.

This morning I entered my password incorrectly 1 time, and MODx returned this error message.

How can I fix this and prevent it from happening in the future?

See http://modxcms.com/forums/index.php?topic=275.0

When you are able to login again, you can raise the number of possible false logins at tools -> configuration on the third tab.

Greetz
JUSI

Additional you can try this (haven’t tesed it myself):
http://modxcms.com/extras/package/476

Greetz
JUSI

I had to run a SQL query:
UPDATE modx_user_attributes SET blockeduntil=0 WHERE id=1;

http://wiki.modxcms.com/index.php/Manager_Lockout


_{been there, unblocked that...}