SPFX version 1.8.2
This error i have now in old projects and new too. Could you help me pls? Whats wrong?

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I can confirm it for field customizers. They still do not work
splistitemsscope-is-mini-458967dd.js:40 Uncaught Error: There is no operation handler registered for '{"operation_4":["getItems_16","detailsListItem_552"]}'.
at t.n (spofiles-mini-0ad3f7bb.js:270)
at new t (splistitemsscope-is-mini-458967dd.js:22)
at splistitemsscope-is-mini-458967dd.js:22
at splistitemsscope-is-mini-458967dd.js:6
at splistitemsscope-is-mini-458967dd.js:10
at splistitemsscope-is-mini-458967dd.js:14
at dispatch (splistitemsscope-is-mini-458967dd.js:5)
at Object.<anonymous> (splistitemsscope-is-mini-458967dd.js:21)
at listviewdataprefetch-mini-e48b7aa0.js:18
at Object.next (listviewdataprefetch-mini-e48b7aa0.js:18)

node --version v10.16.1
npm --version 6.9.0
yo --version 3.1.0
gulp --version CLI version: 2.2.0, Local version: Unknown
npm view webpack version 4.39.3
code -version 1.37.1 f06011ac164ae4dc8e753a3fe7f9549844d15e35 x64
SharePoint Online, modern team site
@Gennady-G I found the issue. It works for me. You have to change the Internal Field Name in serve.json. But... they want from you internal field name, but the internal name gets me this errors. Then I try to use the field display name and tralala..everythink works Example. I'm using Title field (renamed to Process). If I use Title internal name "Title", it doesn't work, if I use renamed Title field
"Process," it works. 馃拑 Try it.
Hi @p333ter !
I tried, but have no luck. I have Field "Percentage" and same internal name "Percentage".

Tried "npm install" and "npm update"
, then
"gulp bundle --ship"
"gulp package-solution --ship"
dropped *.sppkg to 'App Catalog' and scripts to CDN, nothing changes.
Closing the issue as OP resolved their problem. @Gennady-G if you are having an issue, please open your own issue so we don't cross the streams.
But... are you trying to test it or deploy it? Sounds like deployment from your statement:
@Gennady-G said:
dropped *.sppkg to 'App Catalog' and scripts to CDN, nothing changes.
serve.json is only used in testing as it's used to configure the gulp serve task.
Field customizers are associated with new site columns, not existing ones, when deployed. The site column that's created is in the ./sharepoint/assets/elements.xml file. See the docs: https://docs.microsoft.com/en-us/sharepoint/dev/spfx/extensions/get-started/building-simple-field-customizer#add-the-field-definition-to-the-solution-package-for-deployment
@andrewconnell , arghh!..
So when I test it uses existing column with same name, but in production I should deploy Site Column!..
Thank You much Andrew, now it is resolved.
It was not obvious for me..
p.s. this error

still exists in my console log but does not affect my things. Thank You much!
Look closely at that error... does anything in it look like it's coming from your code? Nope... it's all coming from something hosted in Akamai's CDN. IOW, it's not yours so it's not your problem :)
I found the issue. It works for me. You have to change the Internal Field Name in serve.json. But... they want from you internal field name, but the internal name gets me this errors. Then I try to use the field display name and tralala..everythink works Example.
Yes @p333ter , there should be DIsplayName, but it does not allow spaces in this display name.. Fantastic.. :-D
I also found how to attach Field Customizers to existing OOTB fields:
Connect-PnPOnline ..
Set-PnPField -Identity "PercetageField" -List "PercentagesList" -Values @{ClientSideComponentId=[GUID]"6a6cfa85-933b-4a3d-b08f-c2755bb2bae2"}
where guid is id from "YourFieldCustomizer.manifest.json"
Nope... it's all coming from something hosted in Akamai's CDN. IOW, it's not yours so it's not your problem :)
@andrewconnell, no SharePoint - no problems! :-D
By the way - I already commented about this error, but these bugs are closed as duplicates, so I think it is already exists in Your bug tracking system..
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