SSRS The Report Server has Encountered a Configuration Error

I'm running SSRS 2016 on a local machine for development purposes. I've been running into this error quite frequently and spontaneously, as in I will run a report, then 3 minutes later try running the same report with the same parameters and all of a sudden my config is broken without changes. I start mucking around with the configs and eventually, seemingly spontaneously, again it will start working again. Then the cycle continues where it works for 1 hour - a few months before just breaking again.

Here is the screenshot from my Web Service URL:

The actual error message from the log is:

ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.ServerConfigurationErrorException: AuthzInitializeContextFromSid: Win32 error: 1355, Microsoft.ReportingServices.Diagnostics.Utilities.ServerConfigurationErrorException: The report server has encountered a configuration error. ;

When I google that error message I get a bunch of forum posts about sending emails and email configuration but I'm not trying to send emails nor do I have any email stuff configured.

Here is the configuration I'm using under Reporting Services Configuration Manager:

Service Account:

• User Another Account (My Domain Account) I've also tried every combination of built-in account which also seem to work when the server doesn't throw this error..

Web Service URL:

• IP Address: All Assigned
• TCP Port: 80
• HTTPS Cert: N/A
• HHTPS Port: {blank}

Database:

• My Local SQL Server instance and Report DBs using Windows Account login

Email Settings (all default settings):

• Sender Address: {blank}
• Current SMTP Delivery Method: Use SMTP Server (drop down is read only cannot be changed)
• SMTP Server: {blank}
• Authentication: No Authentication

Execution Account:

• Specify an existing Account: unchecked

Subscription Settings:

• Specify a file share account: unchecked

I've also restored and changed encryption keys numerous times and deleted all Encrypted Content under the Encryption Keys Pane. I always use the same snk file for the key and same password so I know it's correct.

If there's any additional information I can provide to help, please let me know. I know this is a bit of a longshot but it's really annoying and impedes my productivity developing SSRS reports.

Thanks in advance.

Well, after more googling, half way down the first page of results I finally came across this article:

https://support.microsoft.com/en-ca/help/3171505/fix-the-service-is-not-available-error-when-you-use-ssrs-2016-portal-a

I downloaded the suggested Cumulative Update 2 for SQL Server 2016 and low and behold, my local setup is working again. Could this be just a coincidence? Absolutely. I will report back if it dies again with the same error but I'm hopeful for the time being.