Terraform fails with empty string errors

[bitglue]

Since updating from master a week or two ago, Terraform has started giving me mystery errors:

$ awsudo terraform refresh
module.dev_vpc.aws_vpc.vpc: Refreshing state... (ID: vpc-3ac99d5f)
module.internal_vpc.aws_vpc.vpc: Refreshing state... (ID: vpc-6aca9e0f)
module.main_registry_storage.aws_iam_role.rw: Refreshing state... (ID: main-docker-registry-rw)
module.main_registry_storage.aws_iam_role.ro: Refreshing state... (ID: main-docker-registry-ro)
module.main_registry_storage.aws_s3_bucket.registry: Refreshing state... (ID: main-docker-registry-paperg-com)
module.main_registry_storage.aws_iam_instance_profile.rw: Refreshing state... (ID: main-docker-registry-rw)
module.main_registry_storage.aws_iam_instance_profile.ro: Refreshing state... (ID: main-docker-registry-ro)
module.dev_vpc.aws_internet_gateway.gateway: Refreshing state... (ID: igw-bd3ca8d8)
Error refreshing state: 1 error(s) occurred:

* 1 error(s) occurred:

* 1 error(s) occurred:

* 

If I run it with TF_LOG=1 and grep for errors, I see a lot of this:

2015/04/17 13:03:09 [ERROR] root.internal_vpc: eval: *terraform.EvalValidateCount, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.internal_vpc: eval: *terraform.EvalOpFilter, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.internal_vpc: eval: *terraform.EvalSequence, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.dev_vpc: eval: *terraform.EvalValidateCount, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.dev_vpc: eval: *terraform.EvalOpFilter, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.dev_vpc: eval: *terraform.EvalSequence, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.main_registry_storage: eval: *terraform.EvalValidateCount, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.main_registry_storage: eval: *terraform.EvalOpFilter, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.main_registry_storage: eval: *terraform.EvalSequence, err: Warnings: []. Errors: []
2015/04/17 13:03:09 [ERROR] root.main_registry_storage: eval: *terraform.EvalValidateCount, err: Warnings: []. Errors: 

I'm confused because it says "1 error(s) occurred:" but then there's no error, and the logs say "[ERROR]" and then explain that there's an empty list of errors.

A guess: I recently deleted some resources through the AWS web console, which is necessary because destroy doesn't work (#922). Running refresh should notice this, and remove the resource from the state file, but it's a common bug for providers to forget about that case (#889). I think I might be hitting such a case somewhere, but without any actual error messages I can only guess.

Sorry I can't narrow it down any more -- I realize this is totally unreproducable. But maybe since this seems like a recent change to master, someone remembers some change that might be relevant.

[bitglue]

Found the issue. I guess it could be considered a bug in the AWS SDK that some of its errors Error() to an empty string, which is about the least useful thing possible. Though, maybe at least the logs generated by TF_LOG=1 could print the error with %#v, or something else more verbose than %s?

[ghost]

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