使用Spring Tool Suite，按照嚮導建立Spring boot starter project，結果，報錯。

Description Resource    Path    Location    Type
Project build error: Non-resolvable parent POM for com.example:demo:0.0.1-SNAPSHOT: Failure to transfer org.springframework.boot:spring-boot-starter-parent:pom:2.0.0.M5 from https://repo.spring.io/snapshot was cached in
 
 the local repository, resolution will not be reattempted until the update interval of spring-snapshots has elapsed or updates are forced. Original error: Could not transfer artifact org.springframework.boot:spring-boot-starter-parent:pom:2.0.0.M5 from/to spring-snapshots (https://repo.spring.io/snapshot): connect timed out and
 
 'parent.relativePath' points at no local POM   pom.xml /demo   line 14 Maven pom Loading Problem

錯誤指向POM.xml的Parent節點。

詳細檢視錯誤提示，發現為TIME OUT。因此，需要重新觸發Maven的Update。

解決方案步驟：

（1）工程–》右鍵–》Maven–》Update Project…

（2）取消offline選項，選擇Force Update of Snapshots/Releases，OK

同步後，問題解決。