Google Analyticsの一部項目名称変更に伴い、レポーティングAPIの名称が変更されています

訪問数 -> セッション
ユニークユーザー数 -> ユーザー

などのAnalytics上の表記変更に伴い、Google AnalyticsのレポーティングAPIの名称も変更になったようです。

詳細はオフィシャルサイトでご確認ください。

Audience
Dimension - ga:visitorAgeBracket - Use ga:userAgeBracket instead.
Dimension - ga:visitorGender - Use ga:userGender instead.

Ecommerce
Metric - ga:transactionRevenuePerVisit - Use ga:transactionRevenuePerSession instead.
Metric - ga:transactionsPerVisit - Use ga:transactionsPerSession instead.

Event Tracking
Metric - ga:eventsPerVisitWithEvent - Use ga:eventsPerSessionWithEvent instead.
Metric - ga:visitsWithEvent - Use ga:sessionsWithEvent instead.

Goal Conversions
Metric - ga:goalValuePerVisit - Use ga:goalValuePerSession instead.

Internal Search
Metric - ga:percentVisitsWithSearch - Use ga:percentSessionsWithSearch instead.
Metric - ga:searchVisits - Use ga:searchSessions instead.

Page Tracking
Metric - ga:pageviewsPerVisit - Use ga:pageviewsPerSession instead.

Session
Dimension - ga:visitLength - Use ga:sessionDurationBucket instead.
Metric - ga:avgTimeOnSite - Use ga:avgSessionDuration instead.
Metric - ga:timeOnSite - Use ga:sessionDuration instead.
Metric - ga:visitBounceRate - Use ga:bounceRate instead.
Metric - ga:visits - Use ga:sessions instead.

Social Interactions
Dimension - ga:socialInteractionNetworkActionVisit - Use ga:socialInteractionNetworkActionSession instead.
Metric - ga:socialInteractionsPerVisit - Use ga:socialInteractionsPerSession instead.

User
Dimension - ga:daysSinceLastVisit - Use ga:daysSinceLastSession instead.
Dimension - ga:visitCount - Use ga:sessionCount instead.
Dimension - ga:visitorType - Use ga:userType instead.
Dimension - ga:visitsToTransaction - Use ga:sessionsToTransaction instead.
Metric - ga:newVisits - Use ga:newUsers instead.
Metric - ga:percentNewVisits - Use ga:percentNewSessions instead.
Metric - ga:visitors - Use ga:users instead.