v4.9.3 intermittent "Error: unexpected value returned by API" for resolved .terragrunt-version

[jportwood01]

Describe the bug

When running 'tenv tg install -v' using tenv v4.9.3, a valid TENV_GITHUB_TOKEN, and .terragrunt-version, we occasionally receive "Error: unexpected value returned by API". There is no indication in the verbose and trace-level logs of what the unexpected value is, or what the actual error was.

16:10:35  TENV_GITHUB_TOKEN length: 40
16:10:35  Installing Terragrunt via 'tenv tg install -v'
16:10:36  + tenv tg install -v
16:10:36  Resolved version from /home/jenkins/workspace/iac_repo_name_master/.terragrunt-version : 0.97.0
16:10:36  Installing Terragrunt 0.97.0
16:10:36  2026-03-11T20:10:36.173Z [DEBUG] tenv: Can not read remote configuration file: error="open /home/jenkins/.tenv/remote.yaml: no such file or directory"
16:10:36  2026-03-11T20:10:36.173Z [DEBUG] tenv: Search: assets=["terragrunt_linux_amd64", "SHA256SUMS"]
16:10:36  Fetching release information from https://api.github.com/repos/gruntwork-io/terragrunt/releases/tags/v0.97.0
16:10:36  Error: unexpected value returned by API

Similar bugs and lack of error information have been reported before:

• Error: unexpected value returned by API on tenv tg install latest #508
• v4.8.3 can't fetch terragrunt releases #517
• Improve error messages in case of unexpected response from the API #236

To Reproduce

This issue has been observed intermittently, but we do not currently have a reliable set of steps to reproduce it consistently.

Expected behavior

Include more detail in error messages, for example:

• Value received: display the unexpected value returned by the API
• Expected value: example of the expected value (if applicable)

Logs for any errors that occurred, such as:

• Timeout
• Rate limit
• Other

Screenshots

N/A

Environment (please complete the following information):

Docker Container:

• platform=linux/amd64 debian:stable
• TENV_VERSION=v4.9.3

Additional context

We have attempted reasonable waits and retries to avoid the error, but without luck.

16:10:35  TENV_GITHUB_TOKEN length: 40
16:10:35  Installing Terragrunt via 'tenv tg install -v'
16:10:36  + tenv tg install -v
16:10:36  Resolved version from /home/jenkins/workspace/iac_repo_name_master/.terragrunt-version : 0.97.0
16:10:36  Installing Terragrunt 0.97.0
16:10:36  2026-03-11T20:10:36.173Z [DEBUG] tenv: Can not read remote configuration file: error="open /home/jenkins/.tenv/remote.yaml: no such file or directory"
16:10:36  2026-03-11T20:10:36.173Z [DEBUG] tenv: Search: assets=["terragrunt_linux_amd64", "SHA256SUMS"]
16:10:36  Fetching release information from https://api.github.com/repos/gruntwork-io/terragrunt/releases/tags/v0.97.0
16:10:36  Error: unexpected value returned by API
16:10:36  Retrying in 10 seconds...

...
waits and tries few more times, same results
...

16:11:18  + tenv tg install -v
16:11:18  Resolved version from /home/jenkins/workspace/iac_repo_name_master/.terragrunt-version : 0.97.0
16:11:18  Installing Terragrunt 0.97.0
16:11:18  2026-03-11T20:11:18.214Z [DEBUG] tenv: Can not read remote configuration file: error="open /home/jenkins/.tenv/remote.yaml: no such file or directory"
16:11:18  2026-03-11T20:11:18.214Z [DEBUG] tenv: Search: assets=["terragrunt_linux_amd64", "SHA256SUMS"]
16:11:18  Fetching release information from https://api.github.com/repos/gruntwork-io/terragrunt/releases/tags/v0.97.0
16:11:18  Error: unexpected value returned by API