github.com/GavinZ8527/viper@v1.7.3-0.20210810015510-af3e089a3405/TROUBLESHOOTING.md (about)

     1  # Troubleshooting
     2  
     3  ## Unmarshaling doesn't work
     4  
     5  The most common reason for this issue is improper use of struct tags (eg. `yaml` or `json`). Viper uses [github.com/mitchellh/mapstructure](https://github.com/mitchellh/mapstructure) under the hood for unmarshaling values which uses `mapstructure` tags by default. Please refer to the library's documentation for using other struct tags.
     6  
     7  ## Cannot find package
     8  
     9  Viper installation seems to fail a lot lately with the following (or a similar) error:
    10  
    11  ```
    12  cannot find package "github.com/hashicorp/hcl/tree/hcl1" in any of:
    13  /usr/local/Cellar/go/1.15.7_1/libexec/src/github.com/hashicorp/hcl/tree/hcl1 (from $GOROOT)
    14  /Users/user/go/src/github.com/hashicorp/hcl/tree/hcl1 (from $GOPATH)
    15  ```
    16  
    17  As the error message suggests, Go tries to look up dependencies in `GOPATH` mode (as it's commonly called) from the `GOPATH`.
    18  Viper opted to use [Go Modules](https://github.com/golang/go/wiki/Modules) to manage its dependencies. While in many cases the two methods are interchangeable, once a dependency releases new (major) versions, `GOPATH` mode is no longer able to decide which version to use, so it'll either use one that's already present or pick a version (usually the `master` branch).
    19  
    20  The solution is easy: switch to using Go Modules.
    21  Please refer to the [wiki](https://github.com/golang/go/wiki/Modules) on how to do that.
    22  
    23  **tl;dr* `export GO111MODULE=on`