DIOP0105EnvironmentReport only
Peer-dependency problem in the installed tree
The package manager reports an invalid, missing or conflicting peer dependency in node_modules.
What it means
Reported from npm ls --json: a library whose peers point at another Angular major, or a peer that is not installed at all. These conflicts are invisible to the declared-range check (DIOP02xx) and are what makes ng update stop with ERESOLVE.
The check runs only for npm projects; pnpm, yarn and bun print the same warnings at install time.
How to fix it
Align the versions before upgrading: usually upgrade the library that requires the other Angular major, or remove it. Do not reach for --legacy-peer-deps first.
What it looks like
As printed by diopter check; the UI and the Markdown report show the same finding with its location.
[DIOP0105] Peer dependency problem in the installed tree: invalid: @angular/core@21.2.12 node_modules/@angular/core, required by ngx-old-lib@3.0.0.In CI
Reported only; it never fails
diopter check.In the UI
The Environment tab, from
diopter next to your dev server, or the static report from diopter build.For agents
MCP tool
audit-peers (diopter mcp).