How did you update?

test Update 3.6.5 > 3.7.0rc1 by Update Channel "Testing" without Error-Warning.

I can confirm notice and error in update from 3.5.1 to 3.7.0Rc1 by Update Channel "Testing"

laoneo: How did you update?

In my case I downloaded and installed the update from this link: https://github.com/joomla/joomla-cms/releases/tag/3.7.0-rc1

No issue here from a 3.6.4 or a 3.6.5 in respect with that.

I tested on a 3.4.5 and it finally works: these are my findings

First we get the error

Then one has to confirm and be presented with an other Confirm

Then update completes

No more error and fields are working.

Therefore, we just have an unwanted error message before the process completes.

@laoneo @Bakual
could it be because the fields system plugin is loaded at this time? I am not sure it should be enabled by default btw.
the language filter plugin is not, why would the fields one be?

The fields system as a whole is turned on by default, so its plugins need to be enabled.

The error comes from JComponentHelper::load. It would be interesting where exactly that is called, because the fields plugin itself doesn't use JComponentHelper as far as I see. It may also come from a completely different place.
That being said, the fields plugin could probably use some checks if com_fields isn't disabled and refuse to work if it is the case.

The fields system as a whole is turned on by default, so its plugins need to be enabled.

I question this decision. Most people will never use that feature. Why should it be turned on by default?

Because most people are not you.

Seriously we have no way of knowing what most people will use.

Steps to reproduce the issue

Update a Joomla 3.7.0 Beta 4 site to Joomla 3.7.0 RC1
Go to the Control Panel
Go to Content > Fields

Result

Error
Unknown column 'a.name' in 'field list'

@webmatrix That's a different issue and a known and expected one due to unsupported upgrade path (from beta to RC). Just renamed the alias column to name in the #__fields table and this is solved.

Yup. Renaming alias column to name solves the issue. Thanks

Closed as expected behaviour as there is no upgrade path from beta to rc

re-opened as I was only commenting on @webmatrix

Error message exists even after update from 3.6.5 to 3.7.0 final.

#15465 should have fixed the case where com_fields for some reason wasn't installed properly.

UPdated from 3.65 to 3.7. 3.65 system uses FlexiContent. FlexiContent seems to take over Joomla Articles. Cannot garner access to Joomla Fields and not finding any plugin or other files related to com_fields.

Constant Warning in Joomla Backend:
Warning
Error loading component: com_fields, Component not found.

please hit the database fixer and try discover install as this sounds like you did not update using com_joomlaupdate. Please move any site spezific issues to forum.joomla.org or the developers of FlexiContent. Thanks.

Fixed the "above" problem by choosing "discover" Under the Extensions/Manage Tab.
There were only about 4 items to "install" (quite old). I choose them, then hit "install".
This in turn brought the new "Fields" and other elements up as potential installs (finally).
Error message went away though I have not actually installed the "fields" named elements as yet.

This page shows up under any relevant searches so seems best to document the solution. Will move my queries to forum.joomla.com and flexicontent. (Relatively undocumented so far)

I am closing this as it was resolved with #15465