Fix Cloudflare R2 Upload Errors — How to Resolve with RcloneView
Cloudflare R2 has specific credential and endpoint requirements that cause errors when misconfigured. Here's how to diagnose and fix the most common R2 upload and sync failures in RcloneView.
Cloudflare R2 is an S3-compatible object storage service that eliminates egress fees, making it attractive for content distribution and backup workloads. However, R2's authentication model differs slightly from standard AWS S3 — it uses an Account ID alongside API tokens rather than the IAM-style key pairs most S3 users are familiar with. Getting these details right in RcloneView is the key to resolving most R2 errors.
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Error: 403 Forbidden or Invalid Credentials
The most common R2 error is a 403 Forbidden response, usually caused by incorrect API token configuration. When adding Cloudflare R2 in Remote tab → New Remote, you need three pieces of information: the R2 API Token (with Object Read/Write permissions for the specific bucket), the Account ID (found in the Cloudflare dashboard), and the R2 endpoint URL in the format https://<ACCOUNT_ID>.r2.cloudflarestorage.com.
A common mistake is using the Global API Key instead of an R2-specific API token. Generate a dedicated API token in Cloudflare's R2 section under Manage API Tokens, and ensure it has at least "Object Read & Write" permissions for the target bucket. If you're getting 403 errors on bucket listing but not on individual file access, the token may lack bucket-level list permissions — regenerate with "Account → R2 → Read/Write" scope.
Error: Multipart Upload Failed or Incomplete Uploads
R2 supports multipart uploads (required for files over 100MB), but incomplete multipart uploads can leave orphaned parts in your bucket and cause subsequent uploads of the same filename to fail. In RcloneView's Log tab, look for messages like upload multipart failed or NoSuchUpload.
The fix is to first clean up orphaned multipart uploads from your R2 bucket using the Cloudflare dashboard or the rclone terminal inside RcloneView. Then retry the upload with a lower number of concurrent multipart streams in the job's Advanced Settings. Setting --s3-upload-concurrency 4 via the Global Rclone Flags option in Settings can stabilize large uploads to R2.
Endpoint and Region Errors
Cloudflare R2 does not use standard AWS region codes. If you see NoSuchBucket or InvalidLocationConstraint errors, verify the endpoint URL in your remote configuration. The correct format is https://<YOUR_ACCOUNT_ID>.r2.cloudflarestorage.com — the account ID must match your Cloudflare account exactly. The region field should be left empty or set to auto for R2.
If you copied the endpoint from a different S3 service, double-check that it starts with your Account ID prefix and not an AWS region URL like s3.us-east-1.amazonaws.com.
Getting Started
- Download RcloneView from rcloneview.com.
- Verify your R2 API Token has Object Read/Write permissions on the target bucket.
- Confirm the endpoint URL uses the format
https://<ACCOUNT_ID>.r2.cloudflarestorage.com. - For large files, reduce multipart upload concurrency and clean up any orphaned uploads.
Correctly configured, Cloudflare R2 with RcloneView offers excellent performance for backup and archiving at predictable cost.
Related Guides:
- Manage Cloudflare R2 Cloud Storage with RcloneView
- Fix S3 Access Denied Permission Errors with RcloneView
- Fix S3 Multipart Upload Failures with RcloneView
Supported Cloud Providers
