Oracle BPM/SOA Human Task: Java code in jsp source files is not allowed in ojsp.next mode

Today I came across an exception while trying to load one of my task details (v12.2.1).

Error: OracleJSP error: oracle.jsp.parse.JavaCodeException: Line # 14, oracle.jsp.parse.JspParseTagScriptlet@66e50889
Error: Java code in jsp source files is not allowed in ojsp.next mode

What was really strange to me was that I did not do anything different from what I used to do with previous versions.

After some research I found out that this was a known issue for 12.2.1. There are two possible causes for getting this error.

a) Either you are not using the fully qualified host name  (including domain name) for the forms to render properly. See Configuring the SOA Human Task Hostname

b) If you indeed using the fully qualified host name for your forms then you should open the default generated login.jsp page and remove the line containing <% ... %> and redeploy the form project.