If you are positive the username and password entered are valid, this likely points to an issue in your login-identity-providers.xml ldap-provider configuration with the manager DN and/or manager password.
Since this is an xml file, the first question to ask is if the password contains any XML special characters (<, >, ", `, or &):
< replace with <
> replace with >
" replace with "
ˋ replace with '
& replace with &
If so, you'll need to escape them by using above substitutions.
Next is to use ldapsearch to verify the manager DN and manager password works using same configuration set in the ldap-provider (minus xml substitutions if any) against the same username and password.
Make sure the results from your ldapsearch on returns one matching user.
I have seen setups where ldap had same username multiple times under different DNs.
This will not work with NiFi login as NiFi would be unable to determine which is the actual user being authenticated. In this scenario, adjust your search base so that it only returns one user entry.
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