I thought that perhaps Scully was causing issues since it had the older versions, but removing it actually resulted in an error (rather than things working properly):

$ ng update @angular/cli
Your global Angular CLI version (10.1.0) is greater than your local
version (10.0.8). The local Angular CLI version is used.

To disable this warning use "ng config -g cli.warnings.versionMismatch false".
The "@angular-devkit/schematics" package cannot be resolved from the workspace root directory. This may be due to an unsupported node modules structure.
Please remove both the "node_modules" directory and the package lock file; and then reinstall.
If this does not correct the problem, please temporarily install the "@angular-devkit/schematics" package within the workspace. It can be removed once the update is complete.
splaktar:xlts.dev splaktar$ npm ls @angular-devkit/schematics
xlts.dev@0.2.0 /Users/splaktar/Git/devintent/xlts/xlts.dev
├─┬ @angular/cli@10.0.8
│ ├── @angular-devkit/schematics@10.0.8 
│ ├─┬ @schematics/angular@10.0.8
│ │ └── @angular-devkit/schematics@10.0.8  deduped
│ └─┬ @schematics/update@0.1000.8
│   └── @angular-devkit/schematics@10.0.8 
└─┬ @schuchard/prettier@3.1.0
  └── @angular-devkit/schematics@7.3.9 

Workaround

With my Scully libs put back in and everything restored to the original state:

1. rm -rf node_modules/
2. rm package-lock.json
3. npm i
4. ng update @angular/cli

Your global Angular CLI version (10.1.0) is greater than your local
version (10.0.8). The local Angular CLI version is used.

To disable this warning use "ng config -g cli.warnings.versionMismatch false".
The installed local Angular CLI version is older than the latest stable version.
Installing a temporary version to perform the update.
Installing packages for tooling via npm.
Installed packages for tooling via npm.
Repository is not clean. Update changes will be mixed with pre-existing changes.
Using package manager: 'npm'
Collecting installed dependencies...
Found 54 dependencies.
Fetching dependency metadata from registry...
    Updating package.json with dependency @angular-devkit/build-angular @ "0.1001.0" (was "0.1000.8")...
    Updating package.json with dependency @angular/cli @ "10.1.0" (was "10.0.8")...
UPDATE package.json (3757 bytes)
✔ Packages installed successfully.
** Executing migrations of package '@angular/cli' **

❯ Removing "Solution Style" TypeScript configuration file support.
DELETE tsconfig.base.json
UPDATE tsconfig.json (795 bytes)
UPDATE tsconfig.spec.json (385 bytes)
UPDATE projects/angularjs.xlts.dev/tsconfig.app.json (190 bytes)
UPDATE projects/xlts.dev/tsconfig.app.json (190 bytes)
  Migration completed.

Questions

Can the situation with The "@angular-devkit/schematics" package cannot be resolved from the workspace root directory. be improved?

• First it didn't find the latest version and used a version from a library that didn't match the version used by the CLI. There was no warning or error here. It seems like there should have been when doing ng update to 10.1 and the update using schematic libs from 9.1.
• Second, it didn't find the schematics package when it was clearly visible to npm ls. Why? Is there a bug in this package resolution code?

I am encountering a similar if not the same problem.

I have tsconfig.base.json(but no tsconfig.json) in the root of my project and get a failure of

[error] Error: Could not read 'tsconfig.json'.
    at new JSONFile (<path_to_repo>/node_modules/@schematics/angular/utility/json-file.js:22:19)

every time I try to run

ng update @angular/cli @angular/core

@cwhaught that seems like a separate issue. Can you please open a new issue for it?

Apologies @Splaktar, I thought I saw the same error in your comments at first glance.

Hi @Splaktar,

Find below the answers to your questions, feel free to ask more 😀.

Can the situation with The "@angular-devkit/schematics" package cannot be resolved from the workspace root directory. be improved?

This should be handled with the new version of schematics, aka schematics runtime, which is still currently in it's early design phase.

• First it didn't find the latest version and used a version from a library that didn't match the version used by the CLI. There was no warning or error here. It seems like there should have been when doing ng update to 10.1 and the update using schematic libs from 9.1.

Maybe we can issue a warning when the installed @angular/cli version and @schematics/angular mismatch.

• Second, it didn't find the schematics package when it was clearly visible to npm ls. Why? Is there a bug in this package resolution code?

While npm ls does list @angular-devkit/schematics, none of these is directly under the root level node_modules directory. This resolution is intended, this is because certain packages with schematics will not have @angular-devkit/schematics as a direct dependency. One such package is @angular/core, in which case having the above node_module structure will cause failures when running ng update @angular/core. Te schematic runtime will handle such situation, however this concept is still in it's early design phase.

Side note: I'd suggest that a lock file maintain is done periodically. Overtime when packages are added and updated, the presence of a lock file will hinder package hoisting and deduping.

There are two quick ways to do such maintainance:

1. If your project is on GitHub, enable Renovate bot lock file maintenance feature..
2. Run rm -rf node_modules package-lock.json && npm i

I ran the following command and it worked out:

ng update @angular/cli --from=10.0.0 --to=10.1.3 --migrateOnly=true

As I forgot to use ng update after updating my packages with npm-check-updates to latest CLI version (v10.1.3).