sql server - Connection string "Login failed for user" -

i'm trying connect database using following connection string:

data source=lordkanelsnegle\sqlexpress;attachdbfilename="c:\program files\microsoft sql server\mssql13.sqlexpress\mssql\data\database.mdf";integrated security=true;multipleactiveresultsets=true 

however, gives me error login failed user "lordkanelsnegle\lord kanelsnegle", despite me being able login exact credentials in ssms shown here.

i've tried adding login security tab within ssms , received error,

confirming login in fact exist (as if me logging in them wasn't evidence enough).

i've read every other post, stackoverflow or other, find regarding failed windows authentication logins sql server none of solutions worked me. ideas?

you should remove attachdbfilename="c:\program files\microsoft sql server\mssql13.sqlexpress\mssql\data\database.mdf connection string.

you don't use localdb functional express edition.

i imagine database permanently attached instance , there no need re-attach it. think if in sql server error log you'll see error saying impossible attach database because it's attached , reason of login failure.

another reason can login not mapped database. in case unless it's sysadmin cannot enter database. , reason reported in error log. server not write reason user in login failed error security reasons sysadmin can find in error log next 18456 error