[Zope] Migrated from Zope 2.7.8 to 2.10; how to fix "Unauthorized: You are not allowed to access 'standard_html_header' in this context" error?

[Aleksey Tsalolikhin]

Hi.  I recently migrated from Zope 2.7.8 to 2.10 and am now seeing
this error in my event.log:


2009-03-28T21:15:52 ERROR root Exception while rendering an error message
Traceback (most recent call last):
  File "/usr/lib/zope/lib/python/OFS/SimpleItem.py", line 225, in
raise_standardErrorMessage
    v = s(client, REQUEST, **kwargs)
  File "/usr/lib/zope/lib/python/OFS/DTMLMethod.py", line 144, in __call__
    r=apply(HTML.__call__, (self, client, REQUEST), kw)
  File "/usr/lib/zope/lib/python/DocumentTemplate/DT_String.py", line
476, in __call__
    try: result = render_blocks(self._v_blocks, md)
Unauthorized: You are not allowed to access 'standard_html_header' in
this context

What does it mean?  How do I fix it, please?

I am new to Zope.

I copied the Web app by export from the old server and import to the new one.

Best,
Aleksey