When upgrading Angular 5 to 6, I get incompatible peer dependency (using ng update @angular/core)

A work around for this would be to add a --force flag.

ng update @angular/core --force

Hope this will help someone else, I finally could solve the issue by manually updating some of the angular packages (using npm)

npm i @angular/cdk@6 @angular/compiler-cli@6 @angular/material@6 rxjs@6 --save

After that the ng update command could work (with some warnings, but at least we passed the ng update @angular/core)

ng update @angular/core    Updating package.json with dependency @angular/language-service @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/animations @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/forms @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/common @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/compiler @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/core @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/router @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/platform-browser-dynamic @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/platform-browser @ "6.0.3" (was "5.2.10")...    Updating package.json with dependency @angular/http @ "6.0.3" (was "5.2.10")...UPDATE package.json (1587 bytes)npm WARN @angular/compiler-cli@6.0.3 requires a peer of typescript@>=2.7.2 <2.8 but none is installed. You must install peer dependencies yourself.npm WARN @angular/flex-layout@5.0.0-beta.14 requires a peer of @angular/cdk@^5.0.0 but none is installed. You must install peer dependencies yourself.npm WARN @angular/flex-layout@5.0.0-beta.14 requires a peer of @angular/core@^5.0.0 but none is installed. You must install peer dependencies yourself.npm WARN @angular/flex-layout@5.0.0-beta.14 requires a peer of @angular/common@^5.0.0 but none is installed. You must install peer dependencies yourself.npm WARN @angular/flex-layout@5.0.0-beta.14 requires a peer of rxjs@^5.5.0 but none is installed. You must install peer dependencies yourself.npm WARN @ngtools/webpack@6.0.3 requires a peer of typescript@~2.4.0 || ~2.5.0 || ~2.6.0 || ~2.7.0 but none is installed. You must install peer dependencies yourself.npm WARN @ngx-translate/http-loader@3.0.1 requires a peer of @ngx-translate/core@>=10.0.0 but none is installed. You must install peer dependencies yourself.npm WARN tsickle@0.27.5 requires a peer of typescript@>=2.4.2 <2.8 but none is installed. You must install peer dependencies yourself.updated 10 packages in 57.253s

The issue was solved for me after making a forced update like the following:-

ng update --all --force

It basically avoids/ignores all the dependency-checks and updates all the packages wherever applicable. Although it is not recommended generally, I had to do the update this way as other suggestions seemed to be not working for me.