Localizing Identity Error Messages

Localizing identity error messages require implementing IdentityErrorDescriber class and override all methods to provide localized/customized error messages using a shared resource file.

Before implementing our own identity error describer we need to define our key error messages in a shared resource files. There is a total of 22 error messages defined in IdentityErrorDescriber class which must be defined in our resource files.

Create a resource file and name it 'LocalizedIdentityErrorMessages.resx', define the below keys with public access modifiers for the neutral language, then create one localized resource files for each culture in the application :

screen shot for localized identity error messages translated using ResX Manager.

Create a new class named LocalizedIdentityErrorDescriber.cs that implements IdentityErrorDescriber and override all methods as below:

// LocalizedIdentityErrorDescriber.cs
public class LocalizedIdentityErrorDescriber : IdentityErrorDescriber
    {
        public override IdentityError DuplicateEmail(string email)
        {
            return new IdentityError
            {
                Code = nameof(DuplicateEmail),
                Description = string.Format(LocalizedIdentityErrorMessages.DuplicateEmail, email)
            };
        }

        public override IdentityError DuplicateUserName(string userName)
        {
            return new IdentityError
            {
                Code = nameof(DuplicateUserName),
                Description = string.Format(LocalizedIdentityErrorMessages.DuplicateUserName, userName)
            };
        }

        public override IdentityError InvalidEmail(string email)
        {
            return new IdentityError
            {
                Code = nameof(InvalidEmail),
                Description = string.Format(LocalizedIdentityErrorMessages.InvalidEmail, email)
            };
        }

        public override IdentityError DuplicateRoleName(string role)
        {
            return new IdentityError
            {
                Code = nameof(DuplicateRoleName),
                Description = string.Format(LocalizedIdentityErrorMessages.DuplicateRoleName, role)
            };
        }

        public override IdentityError InvalidRoleName(string role)
        {
            return new IdentityError
            {
                Code = nameof(InvalidRoleName),
                Description = string.Format(LocalizedIdentityErrorMessages.InvalidRoleName, role)
            };
        }

        public override IdentityError InvalidToken()
        {
            return new IdentityError
            {
                Code = nameof(InvalidToken),
                Description = LocalizedIdentityErrorMessages.InvalidToken
            };
        }

        public override IdentityError InvalidUserName(string userName)
        {
            return new IdentityError
            {
                Code = nameof(InvalidUserName),
                Description = string.Format(LocalizedIdentityErrorMessages.InvalidUserName, userName)
            };
        }

        public override IdentityError LoginAlreadyAssociated()
        {
            return new IdentityError
            {
                Code = nameof(LoginAlreadyAssociated),
                Description = LocalizedIdentityErrorMessages.LoginAlreadyAssociated
            };
        }

        public override IdentityError PasswordMismatch()
        {
            return new IdentityError
            {
                Code = nameof(PasswordMismatch),
                Description = LocalizedIdentityErrorMessages.PasswordMismatch
            };
        }

        public override IdentityError PasswordRequiresDigit()
        {
            return new IdentityError
            {
                Code = nameof(PasswordRequiresDigit),
                Description = LocalizedIdentityErrorMessages.PasswordRequiresDigit
            };
        }

        public override IdentityError PasswordRequiresLower()
        {
            return new IdentityError
            {
                Code = nameof(PasswordRequiresLower),
                Description = LocalizedIdentityErrorMessages.PasswordRequiresLower
            };
        }

        public override IdentityError PasswordRequiresNonAlphanumeric()
        {
            return new IdentityError
            {
                Code = nameof(PasswordRequiresNonAlphanumeric),
                Description = LocalizedIdentityErrorMessages.PasswordRequiresNonAlphanumeric
            };
        }

        public override IdentityError PasswordRequiresUniqueChars(int uniqueChars)
        {
            return new IdentityError
            {
                Code = nameof(PasswordRequiresUniqueChars),
                Description = string.Format(LocalizedIdentityErrorMessages.PasswordRequiresUniqueChars, uniqueChars)
            };
        }

        public override IdentityError PasswordRequiresUpper()
        {
            return new IdentityError
            {
                Code = nameof(PasswordRequiresUpper),
                Description = LocalizedIdentityErrorMessages.PasswordRequiresUpper
            };
        }

        public override IdentityError PasswordTooShort(int length)
        {
            return new IdentityError
            {
                Code = nameof(PasswordTooShort),
                Description = string.Format(LocalizedIdentityErrorMessages.PasswordTooShort, length)
            };
        }

        public override IdentityError UserAlreadyHasPassword()
        {
            return new IdentityError
            {
                Code = nameof(UserAlreadyHasPassword),
                Description = LocalizedIdentityErrorMessages.UserAlreadyHasPassword
            };
        }

        public override IdentityError UserAlreadyInRole(string role)
        {
            return new IdentityError
            {
                Code = nameof(UserAlreadyInRole),
                Description = string.Format(LocalizedIdentityErrorMessages.UserAlreadyInRole, role)
            };
        }

        public override IdentityError UserNotInRole(string role)
        {
            return new IdentityError
            {
                Code = nameof(UserNotInRole),
                Description = string.Format(LocalizedIdentityErrorMessages.UserNotInRole, role)
            };
        }

        public override IdentityError UserLockoutNotEnabled()
        {
            return new IdentityError
            {
                Code = nameof(UserLockoutNotEnabled),
                Description = LocalizedIdentityErrorMessages.UserLockoutNotEnabled
            };
        }

        public override IdentityError RecoveryCodeRedemptionFailed()
        {
            return new IdentityError
            {
                Code = nameof(RecoveryCodeRedemptionFailed),
                Description = LocalizedIdentityErrorMessages.RecoveryCodeRedemptionFailed
            };
        }

        public override IdentityError ConcurrencyFailure()
        {
            return new IdentityError
            {
                Code = nameof(ConcurrencyFailure),
                Description = LocalizedIdentityErrorMessages.ConcurrencyFailure
            };
        }

        public override IdentityError DefaultError()
        {
            return new IdentityError
            {
                Code = nameof(DefaultError),
                Description = LocalizedIdentityErrorMessages.DefaultIdentityError
            };
        }
    }

Add the localized error describer to identity setup under ConfigureServices method in startup class:

// Startup.cs
services.AddIdentity()
        // localize identity error messages
        .AddErrorDescriber()
        .AddEntityFrameworkStores()
        .AddDefaultTokenProviders();
 

Notice: extra lines removed from this code snippet for simply showing required code only.