Error: Local workspace file (‘angular.json’) could not be found

I have travis-ci integrated with my GitHub account (https://github.com/pradeep0601/Angular5-Router-App). When I updated @angular/cli version from 1.7.4 to 6.0.0-rc.3, the build started failing with an error: Local workspace file (‘angular.json’) could not be found. Error: Local workspace file (‘angular.json’) could not be found. at WorkspaceLoader._getProjectWorkspaceFilePath (/home/travis/build/pradeep0601/Angular5-Router-App/node_modules/@angular/cli/models/workspace-loader.js:37:19) at WorkspaceLoader.loadWorkspace (/home/travis/build/pradeep0601/Angular5-Router-App/node_modules/@angular/cli/models/workspace-loader.js:24:21) at TestCommand._loadWorkspaceAndArchitect (/home/travis/build/pradeep0601/Angular5-Router-App/node_modules/@angular/cli/models/architect-command.js:177:32) at TestCommand.<anonymous> (/home/travis/build/pradeep0601/Angular5-Router-App/node_modules/@angular/cli/models/architect-command.js:45:25) at … Read more