Cryptic deployment failure errors

[Samuel Richardson]

Beginning deployment of service [default]...

WARNING: Deployment of service [default] will ignore the skip_files field in the configuration file, because the image has already been built.

Updating service [default] (this may take several minutes)...

.....................failed.

ERROR: (gcloud.app.deploy) Error Response: [13] Deployment Manager operation failed, name: operation-1513229874182-56046491d3770-72b2e55f-bdbf181b, error: [{"code":"CONDITION_NOT_MET","location":"/deployments/aef-default-50474e3/resources/aef-default-50474e3-00it->$.properties","message":"\"/properties/metadata/items/12/value\": domain: validation; keyword: type; message: instance does not match any allowed primitive type; allowed: [\"string\"]; found: \"number\""}]

Exited with code 1

I'm not quite sure how to debug this, Googling random strings in the error message doesn't return any meaningful results. Previous builds were being deployed correctly. Any ideas on where to start to fix this!?

[George (Cloud Platform Support)]

Hello Samuel, 

Is your SDK up-to-date? You may try running the gcloud components update and then gcloud info. What is the output of this last command? Trying again gcloud.app.deploy may then succeed. 

If the above steps do not fix your issue, it is worthwhile running the "gcloud config set app/use_deprecated_preparation True" command.