Upgrading 6.1.1 to 6.1.2 - Unexpected error whilst trying to apply transform chain

lheagney · August 20, 2025, 11:38am

Hi,

I have a site running plone 6.1.1, which I updated to 6.1.2 yesterday via buildout. This completed OK and I can start the site, but instance.log records the following errors:

2025-08-20 12:06:49,442 ERROR   [plone.transformchain:60][waitress-0] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable
2025-08-20 12:06:49,442 ERROR   [plone.transformchain:60][waitress-0] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable
2025-08-20 12:06:49,668 WARNING [waitress.queue:113][MainThread] Task queue depth is 1
2025-08-20 12:08:56,427 ERROR   [plone.transformchain:60][waitress-1] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable
2025-08-20 12:08:56,427 ERROR   [plone.transformchain:60][waitress-1] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable
2025-08-20 12:08:56,559 WARNING [waitress.queue:113][MainThread] Task queue depth is 1
2025-08-20 12:09:01,605 ERROR   [plone.transformchain:60][waitress-0] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable
2025-08-20 12:09:01,605 ERROR   [plone.transformchain:60][waitress-0] Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.transformchain-3.0.1-py3.12.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/web/terahertzsystems-plone6/terahertzsystems/eggs/plone.app.theming-5.0.13-py3.12.egg/plone/app/theming/transform.py", line 183, in transformIterable
    transformed = transform(result.tree, **params)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src/lxml/xslt.pxi", line 596, in lxml.etree.XSLT.__call__
lxml.etree.XSLTApplyError: Undefined variable

This site has numerous problems:

The text for all page titles and sub tilles appears in "viewlet-above-content-title" (but not when logged in as admin)
When editing any content the text of the page just appears in the editor as "Text", and the editor
Resource Registries is reporting that " Javascript disabled or error(s) occurred If this message persists, a Javascript Error occurred within the resources below."

My buildout file is very simple:

[buildout]
extends = https://dist.plone.org/release/6.1.2/versions.cfg
parts = instance

[instance]
recipe = plone.recipe.zope2instance
eggs =
	Plone
	plone.volto
user=admin:XXXXXXXXXX
http-address = 9090

[versions]
packaging=25.0
pip=25.1.1
setuptools=80.9.0
wheel=0.46.1
zc.buildout=4.1.12

I guess these issue are related to the transform chain error above. Any ideas how I can fix this?

Thanks,

Lee.

lheagney · August 20, 2025, 12:06pm

An update....

I rolled this site back to the backup I took of 6.1.1 before updating to 6.1.2 and I noticed that the errors were still there...

A bit of digging has shown that this is not a plone issue. the Apache config that sits in fron of plone was updated to "improve security" and this was the cause.

The config that caused this issue was:

Header set Content-Security-Policy "default-src 'self'

I've changed this to:

Header set Content-Security-Policy "default-src 'self' 'unsafe-inline'

All works as expected on 6.1.2 now.

avoinea · November 18, 2025, 3:16pm

How would the lxml error have anything with CSP?! I get the same error in Plone 6.1.3. The CSS for Plone Classic is broken and I can’t run the upgrades from 6.0.15 to 6.1.3:

Starting the migration from version: 6026
Ran upgrade step: Miscellaneous
Ran upgrade step: Miscellaneous
Ran upgrade step: Miscellaneous
Upgrade aborted. Error:
Traceback (most recent call last):
File "/app/lib/python3.12/site-packages/Products/CMFPlone/MigrationTool.py", line 291, in upgrade
step\["step"\].doStep(setup)
File "/app/lib/python3.12/site-packages/Products/GenericSetup/upgrade.py", line 191, in doStep
self.handler(tool)
File "/app/lib/python3.12/site-packages/plone/app/upgrade/v61/alpha.py", line 33, in add_feature_tinymce_accordion_plugin
plugins_record.value = old_value_plugins
^^^^^^^^^^^^^^^^^^^^
File "/app/lib/python3.12/site-packages/plone/registry/record.py", line 79, in \_set_value
field.validate(value)
File "/app/lib/python3.12/site-packages/zope/schema/\_bootstrapfields.py", line 295, in validate
self.\_validate(value)
File "/app/lib/python3.12/site-packages/zope/schema/\_field.py", line 772, in \_validate
raise WrongContainedType(
zope.schema.\_bootstrapinterfaces.WrongContainedType: (\[ConstraintNotSatisfied('hr', ''), ConstraintNotSatisfied('noneditable', ''), ConstraintNotSatisfied('paste', ''), ConstraintNotSatisfied('print', ''), ConstraintNotSatisfied('tabfocus', '')\], 'value')
End of upgrade path, main migration has finished.
The upgrade path did NOT reach current version.
Migration has failed

avoinea · November 18, 2025, 3:17pm

github.com/plone/plone.app.upgrade

Upgrade from Plone 6.0.15 to 6.1.3 is broken

opened 12:46PM - 06 Oct 25 UTC

closed 06:03AM - 09 Oct 25 UTC

petschki

01 type: bug

There is an upgradestep introduced in https://github.com/plone/plone.app.upgrade…/pull/325 which adds the `TinyMCE.accordion` plugin by (re-)setting the complete `plone.plugins` registry record with the new value. The problem is, that in the meantime we've cleaned the tiny plugins and removed everything which is not valid since Tiny 6+ (https://github.com/plone/plone.app.upgrade/pull/347) ... so re-setting the old schema value for `plugins` doesn't work, because there are invalid vocabulary terms and you end up with the following traceback: ``` 2025-10-06 14:37:04,216 ERROR [plone.app.upgrade:297][waitress-3] Upgrade aborted. Error: Traceback (most recent call last): File "/Users/peterm/workspace/gbd/eggs/Products.CMFPlone-6.1.3-py3.13.egg/Products/CMFPlone/MigrationTool.py", line 291, in upgrade step["step"].doStep(setup) ~~~~~~~~~~~~~~~~~~~^^^^^^^ File "/Users/peterm/workspace/gbd/eggs/Products.GenericSetup-5.0.0-py3.13.egg/Products/GenericSetup/upgrade.py", line 191, in doStep self.handler(tool) ~~~~~~~~~~~~^^^^^^ File "/Users/peterm/workspace/gbd/src/plone.app.upgrade/src/plone/app/upgrade/v61/alpha.py", line 33, in add_feature_tinymce_accordion_plugin plugins_record.value = old_value_plugins ^^^^^^^^^^^^^^^^^^^^ File "/Users/peterm/workspace/gbd/eggs/plone.registry-2.0.2-py3.13.egg/plone/registry/record.py", line 79, in _set_value field.validate(value) ~~~~~~~~~~~~~~^^^^^^^ File "/Users/peterm/workspace/gbd/eggs/zope.schema-7.0.1-py3.13.egg/zope/schema/_bootstrapfields.py", line 295, in validate self._validate(value) ~~~~~~~~~~~~~~^^^^^^^ File "/Users/peterm/workspace/gbd/eggs/zope.schema-7.0.1-py3.13.egg/zope/schema/_field.py", line 772, in _validate raise WrongContainedType( errors, self.__name__ ).with_field_and_value(self, value) zope.schema._bootstrapinterfaces.WrongContainedType: ([ConstraintNotSatisfied('hr', ''), ConstraintNotSatisfied('noneditable', ''), ConstraintNotSatisfied('paste', ''), ConstraintNotSatisfied('print', ''), ConstraintNotSatisfied('tabfocus', '')], 'value') 2025-10-06 14:37:04,219 INFO [plone.app.upgrade:306][waitress-3] End of upgrade path, main migration has finished. 2025-10-06 14:37:04,219 ERROR [plone.app.upgrade:309][waitress-3] The upgrade path did NOT reach current version. 2025-10-06 14:37:04,219 ERROR [plone.app.upgrade:310][waitress-3] Migration has failed ```

petschki · November 23, 2025, 12:58pm

Fixed in plone.app.upgrade==3.3.1 … note, that you have to pin this version yourself, because versions in dist.plone.org are on 3.3.0