{"record":{"id":"725b47fedb637713","repo":"windmill-labs/windmill","slug":"error-writing-file-to-path-e","errorCode":null,"errorMessage":"error writing file to {path}: {e:#}","messagePattern":"error writing file to (.+?): (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"backend/windmill-api-settings/src/lib.rs","lineNumber":341,"sourceCode":"                    \"Failed to list files in blob storage: {e:#}\"\n                )));\n            }\n            Some(Ok(first_file)) => tracing::info!(\"Listed files: {:?}\", first_file),\n            None => tracing::info!(\"No files in blob storage\"),\n        }\n\n        let path = windmill_object_store::object_store_reexports::Path::from(format!(\n            \"/test-s3-bucket-{uuid}\",\n            uuid = uuid::Uuid::new_v4()\n        ));\n        tracing::info!(\"Testing blob storage at path: {path}\");\n        client\n            .put(\n                &path,\n                windmill_object_store::object_store_reexports::PutPayload::from_static(b\"hello\"),\n            )\n            .await\n            .map_err(|e| anyhow::anyhow!(\"error writing file to {path}: {e:#}\"))?;\n        let content = client\n            .get(&path)\n            .await\n            .map_err(to_anyhow)?\n            .bytes()\n            .await\n            .map_err(to_anyhow)?;\n        if content != Bytes::from_static(b\"hello\") {\n            return Err(error::Error::internal_err(\n                \"Failed to read back from blob storage\".to_string(),\n            ));\n        }\n        client.delete(&path).await.map_err(to_anyhow)?;\n        Ok::<String, error::Error>(\"Tested blob storage successfully\".to_string())\n    };\n\n    if restrict {\n        // The object-store client is built with timeouts disabled, so a malicious endpoint could","sourceCodeStart":323,"sourceCodeEnd":359,"githubUrl":"https://github.com/windmill-labs/windmill/blob/e474e8803ce2ff5c2df09a58dab51d45f5c922ca/backend/windmill-api-settings/src/lib.rs#L323-L359","documentation":"test_s3_bucket verifies an S3-compatible storage configuration by writing a small object ('hello') to the given path with the object_store client, then reading it back. If the put fails, the error is wrapped as 'error writing file to {path}: {e:#}' so the underlying object-store error (auth, bucket missing, network) is preserved.","triggerScenarios":"Testing an S3 storage resource/connection in workspace settings where the put operation fails: wrong access/secret key, nonexistent bucket, wrong endpoint/region, missing s3:PutObject permission, or unreachable S3 endpoint.","commonSituations":"Misconfigured S3 resource (bad endpoint URL, region mismatch, typo'd bucket name), IAM policy lacking PutObject, MinIO/CEPH endpoint using http vs https incorrectly, expired credentials.","solutions":["Verify the S3 resource settings (bucket, endpoint, region, access key, secret) in workspace or instance settings","Test credentials with the AWS CLI: aws s3 cp test.txt s3://<bucket>/ to isolate permissions","Check IAM/bucket policy grants s3:PutObject (and GetObject) to the used principal","Confirm endpoint URL scheme (http/https) and reachability/network egress to the S3 endpoint"],"exampleFix":"// before (wrong endpoint)\nendpoint: https://s3.amazonaws.com (bucket is on MinIO)\n// after\nendpoint: http://minio.internal:9000","handlingStrategy":"try-catch","validationCode":"// pre-flight checks before calling test_s3_bucket\nassert!(!bucket.is_empty(), \"bucket must be set\");\nassert!(endpoint.starts_with(\"http\"), \"endpoint must be a URL\");\n// verify credentials/permissions out-of-band:\n// aws s3api head-bucket --bucket <bucket>","typeGuard":null,"tryCatchPattern":"match test_s3_bucket(client, path).await {\n    Ok(_) => info!(\"S3 storage OK\"),\n    Err(e) if e.to_string().contains(\"error writing file\") => {\n        error!(\"S3 put failed: {e:#}\"); // inspect inner object-store cause\n        show_storage_config_help(&e);\n    }\n    Err(e) => return Err(e),\n}","preventionTips":["Validate S3 resource fields (bucket, endpoint, region, keys) before saving","Grant s3:PutObject/GetObject to the IAM principal used","Test connectivity to the endpoint from the Windmill host","Keep endpoint scheme (http/https) consistent with the storage service"],"tags":["s3","storage","network","aws"],"backgroundTag":"s3-write-failed","analyzedSha":"e474e8803ce2ff5c2df09a58dab51d45f5c922ca","analyzedAt":"2026-09-03T12:38:19.024Z","contentChangedAt":"2026-09-03T12:38:19.024Z","schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}