We 
announced an update to 
Customer Match requirements in October 2018 that affects member uploads and the usage of Customer Match for campaigns on Search, YouTube, and Gmail.
  - Creating a CrmBasedUserList through AdWordsUserListService now requires whitelisting. If the account is not whitelisted, your request returns an ADVERTISER_NOT_WHITELISTED_FOR_USING_UPLOADED_DATAerror.
- Uploading members to a CrmBasedUserListresults in aCAN_NOT_MUTATE_SENSITIVE_USERLISTerror if the account is not whitelisted.
- Targeting CrmBasedUserListsin accounts that are not whitelisted using CampaignCriterionService or AdGroupCriterionService results in anINVALID_IDerror.
- Serving campaigns can be affected if they are using Customer Match and the account is not whitelisted. If a campaign is only targeting Customer Match, then the campaign stops serving. If the campaign has other audiences, then the campaign continues to serve with the other audiences.
Please see 
the requirements for whitelist eligibility. To apply for the whitelist, reach out to your account manager. Once whitelisted, Customer Match no longer results in errors and serves normally without any further changes needed.
If you have questions, please reach out to us on the 
AdWords API forum.
 Nadine Sundquist, AdWords API Team
 Nadine Sundquist, AdWords API Team