I don't know exactly how to describe it but as reported in SUPPORT-5028 Magnolia 5.4.1 is not backwards compatible with regards to our custom (FTL-based) login pages which we load as resources.

We have the following use case which we use in Magnolia 5.3 (and earlier) but which no longer works in 5.4.1:

Situation in 5.3:

• we have a custom login page in our custom module located in: /src/main/resources/mgnl-resources/custom-website/custom-login-form/custom-login-form.ftl. this login page contains Freemarker Magnolia logic such as:

   [#if ctx.user.name == 'anonymous']

• we have configured our website to use this login form (when a user attempts to access secure content) in the securityCallbackFilter: /mgnl-resources/custom-website/custom-login-form/custom-login-form.ftl

Because of this issue we cannot migrate our projects to Magnolia 5.4 at this stage (without losing functionality).