This is a common encryption key mismatch issue. Based on the [community.n8n.io](ERROR:Credentials could not be decrypted. The likely reason is that a different "encryptionKey" was used to encrypt the data) discussions, your credentials were encrypted with a different key than what’s currently set.
Here are the steps to resolve this:
• **Stop n8n completely** and ensure your `N8N_ENCRYPTION_KEY` environment variable is properly set before starting
• **If you have a backup** of your original encryption key, use that instead
• **If the key is lost**, you’ll need to delete and recreate all your credentials after n8n starts
• **For the proxy error**, set `HTTP_PROXY=“”` and `HTTPS_PROXY=“”` in your environment variables to disable proxy attempts
The [github.com](Credentials could not be decrypted. · Issue #12949 · n8n-io/n8n · GitHub) issue shows this often happens after updates when the encryption key changes. Make sure to set the encryption key as an environment variable before starting n8n, not after.