Migration from MySQL to PostgreSQL via source not working

I used this guide: https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/update/mysql_to_postgresql.md

On calling sudo -u postgres pgloader commands.load I get the following error message:

2018-07-06T02:27:01.450000Z WARNING Source column "public"."uploads"."id" is casted to type "bigserial" which is not the same as "integer", the type of current target database column "public"."uploads"."id".
2018-07-06T02:27:01.450000Z WARNING Source column "public"."uploads"."size" is casted to type "numeric" which is not the same as "bigint", the type of current target database column "public"."uploads"."size".
2018-07-06T02:27:01.450000Z WARNING Source column "public"."uploads"."model_id" is casted to type "bigint" which is not the same as "integer", the type of current target database column "public"."uploads"."model_id".
2018-07-06T02:27:01.450000Z WARNING Source column "public"."uploads"."created_at" is casted to type "timestamptz" which is not the same as "timestamp without time zone", the type of current target database column "public"."uploads"."created_at".
2018-07-06T02:27:01.451000Z ERROR Database error 0A000: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "web_hooks" references "projects".
HINT: Truncate table "web_hooks" at the same time, or use TRUNCATE ... CASCADE.
QUERY: TRUNCATE public.abuse_reports,public.appearances,public.application_settings,public.audit_events,public.award_emoji,public.boards,public.broadcast_messages,public.chat_names,public.chat_teams,public.ci_builds,public.ci_build_trace_sections,public.ci_build_trace_section_names,public.ci_group_variables,public.ci_job_artifacts,public.ci_pipelines,public.ci_pipeline_schedules,public.ci_pipeline_schedule_variables,public.ci_pipeline_variables,public.ci_runners,public.ci_runner_projects,public.ci_stages,public.ci_triggers,public.ci_trigger_requests,public.ci_variables,public.clusters,public.clusters_applications_helm,public.clusters_applications_ingress,public.cluster_platforms_kubernetes,public.cluster_projects,public.cluster_providers_gcp,public.container_repositories,public.conversational_development_index_metrics,public.deployments,public.deploy_keys_projects,public.emails,public.environments,public.events,public.features,public.feature_gates,public.forked_project_links,public.fork_networks,public.fork_network_members,public.gcp_clusters,public.gpg_keys,public.gpg_key_subkeys,public.gpg_signatures,public.group_custom_attributes,public.identities,public.issues,public.issue_assignees,public.issue_metrics,public.keys,public.labels,public.label_links,public.label_priorities,public.lfs_objects,public.lfs_objects_projects,public.lists,public.members,public.merge_requests,public.merge_requests_closing_issues,public.merge_request_diffs,public.merge_request_diff_commits,public.merge_request_diff_files,public.merge_request_metrics,public.milestones,public.namespaces,public.notes,public.notification_settings,public.oauth_access_grants,public.oauth_access_tokens,public.oauth_applications,public.oauth_openid_requests,public.pages_domains,public.personal_access_tokens,public.projects,public.project_authorizations,public.project_auto_devops,public.project_custom_attributes,public.project_features,public.project_group_links,public.project_import_data,public.project_statistics,public.protected_branches,public.protected_branch_merge_access_levels,public.protected_branch_push_access_levels,public.protected_tags,public.protected_tag_create_access_levels,public.push_event_payloads,public.redirect_routes,public.releases,public.routes,public.sent_notifications,public.services,public.snippets,public.spam_logs,public.subscriptions,public.system_note_metadata,public.taggings,public.tags,public.timelogs,public.todos,public.trending_projects,public.u2f_registrations,public.uploads;
2018-07-06T02:27:01.451000Z FATAL Failed to create the schema, see above.
2018-07-06T02:27:01.451000Z LOG report summary reset
       table name     errors       rows      bytes      total time
-----------------  ---------  ---------  ---------  --------------
  fetch meta data          0        105                     0.248s
         Truncate          0          0                     0.000s
-----------------  ---------  ---------  ---------  --------------
-----------------  ---------  ---------  ---------  --------------

The error message is:

2018-07-06T02:27:01.451000Z ERROR Database error 0A000: cannot truncate a table referenced in a foreign key constraint
DETAIL: Table "web_hooks" references "projects".
HINT: Truncate table "web_hooks" at the same time, or use TRUNCATE ... CASCADE.

It's that any idea to solve this probrem ?