I had a scenario like when migrating a named credential with password in salesforce production. I resolved that issue so I came here to give a solution for Password error problem.

 

   1. Retrieve a Named credential from Ant Migration tool

   2. XML will Look like this,

 

 

           <?xml version="1.0" encoding="UTF-8"?>

               <NamedCredential xmln="http://soap.sforce.com/2006/04/metadata">

                        <endpoint>https://prodbox-dev.herokuapp.com/v1</endpoint>

                        <label>prodbox_heroku</label>

                        <principalType>NamedUser</principalType>

                        <protocol>Password</protocol>

                        <username>technical.user.prod@techuser.dev</username>

               </NamedCredential>

 

 

When i deploy the same using ant, it displays error for password.

 

So I added a password manually after retrieve. 

 

 

      <?xml version="1.0" encoding="UTF-8"?>

              <NamedCredential xmln="http://soap.sforce.com/2006/04/metadata">

                        <endpoint>https://prodbox-dev.herokuapp.com/v1</endpoint>

                        <label>prodbox_heroku</label>

                        <principalType>NamedUser</principalType>

                        <protocol>Password</protocol>

                        <password>actual Password</password>

                        <username>technical.user.prod@techuser.dev</username>

              </NamedCredential>