GCP中无法创建App Engine应用的异常问题求助

按照公开实验文档步骤部署应用时，遇到一系列矛盾的错误：

执行gcloud app deploy报错 #

运行部署命令时，系统提示需创建App Engine应用，选择us-west1区域后报错：

$ gcloud app deploy
You are creating an app for project [sfsu-pic-a-daily-lab-1].
WARNING: Creating an App Engine application for a project is irreversible and the region
cannot be changed. More information about regions is at
<https://cloud.google.com/appengine/docs/locations>.

Please choose the region where you want your App Engine application located:

[省略区域列表]
Please enter your numeric choice:  20

ERROR: (gcloud.app.deploy) The project [sfsu-pic-a-daily-lab-1] already contains an App Engine application. You can deploy your application using `gcloud app deploy`.

错误说明：系统声称项目已存在App Engine应用，要求直接部署，但实际从未创建过该应用。

查询应用状态的矛盾结果 #

执行命令查询应用状态，均提示项目无App Engine应用：

$ gcloud app instances list
ERROR: (gcloud.app.instances.list) Apps instance [sfsu-pic-a-daily-lab-1] not found: App does not exist.

$ gcloud app browse
ERROR: (gcloud.app.browse) The current Google Cloud project [sfsu-pic-a-daily-lab-1] does not contain an App Engine application. Use `gcloud app create` to initialize an App Engine application within the project.

执行gcloud app create仍失败 #

尝试手动创建应用，选择us-west1区域后依旧报错：

$ gcloud app create
You are creating an app for project [sfsu-pic-a-daily-lab-1].
WARNING: Creating an App Engine application for a project is irreversible and the region
cannot be changed. More information about regions is at
<https://cloud.google.com/appengine/docs/locations>.

[省略区域列表]
Please enter your numeric choice:  20

ERROR: (gcloud.app.create) The project [sfsu-pic-a-daily-lab-1] already contains an App Engine application. You can deploy your application using `gcloud app deploy`.

控制台创建应用失败 #

在Google Cloud控制台UI中尝试创建App Engine应用同样失败：

更新：关联Firestore错误 #

后续发现Firestore相关错误，揭示冲突根源：

Already exists (HTTP 409): Cannot create Firestore database resource projects/sfsu-pic-a-daily-lab-1/databases/(default) since it is already exists at location nam5.

错误说明：项目的默认Firestore数据库已在nam5区域存在，导致App Engine创建时因区域冲突失败。

• 先确认Firestore状态：登录Google Cloud控制台，进入Firestore页面，查看现有数据库的区域（nam5）
• 使用Firestore已存在的区域创建App Engine应用：执行命令 gcloud app create --region=nam5
• 若命令执行异常，检查项目是否有遗留配置：通过控制台查看App Engine设置页面，确认是否存在隐藏的应用记录；或使用gcloud app describe命令尝试获取应用信息
• 若以上方法无效，联系Google Cloud技术支持，提供项目ID和完整错误日志，排查后端状态不一致问题

内容的提问来源于stack exchange，提问作者wintermute