1. File Too Large
Error: "File exceeds maximum size limit for your tier"
Cause: Your file exceeds the upload limit for your plan tier.
Size limits by tier:
- Guest — 25 MB per file
- Free — 25 MB per file
- Pro — 200 MB per file
- Business — 1024 MB per file
Solutions:
- Upgrade to a higher tier for larger file limits
- Split large files if possible (e.g., multi-page PDFs)
2. Unsupported Format
Error: "File format not supported for this compressor"
Cause: The file extension or MIME type doesn't match what the compressor expects.
Supported formats:
- Images — JPG, PNG, WebP, AVIF
- Documents — PDF
Solutions:
- Use the correct compressor for your file type
- Verify the file's actual format (extension may be misleading)
- If your format isn't supported, request it
3. Corrupted or Invalid File
Error: "File appears to be corrupted or invalid"
Cause: The file failed integrity checks or our pipeline couldn't decode it.
Common causes:
- Incomplete download from camera/cloud storage
- File truncated during transfer
- Filesystem corruption
- Renamed file with wrong extension
Solutions:
- Re-download or re-export the original file
- Try opening the file locally to verify it's valid
4. Password-Protected PDF
Error: "This PDF is password-protected and cannot be compressed"
Cause: The PDF requires a password to open or has security restrictions that prevent processing.
Solutions:
- Remove password protection in Adobe Acrobat (File → Properties → Security → No Security)
- Use an online PDF unlock tool to remove protection
- If you don't have the password, contact the PDF creator
5. Batch Size Exceeded
Error: "Too many files in batch for your tier"
Cause: You're trying to upload more files than your plan allows in a single batch.
Batch limits by tier:
- Guest — 50 files per batch
- Free — 50 files per batch
- Pro — 200 files per batch
- Business — 1000 files per batch
Solutions:
- Split your files into smaller batches
- Upgrade to a higher tier for larger batch limits
6. Queue at Capacity
Error: "Queue is currently at capacity. Please try again."
Cause: The job queue has reached its limit. This is rare and typically clears quickly.
Solutions:
- Wait 30-60 seconds and try again
- If persistent, check status.tools.fast for incidents
7. Daily Limit Reached
Error: "Daily usage limit exceeded"
Cause: Free tier users have daily compression limits.
- Guest — 50 compressions per day
- Free — 50 compressions per day
Solutions:
- Wait until tomorrow (limits reset at midnight)
- Create a free account to get your own credit pool
- Upgrade to Pro for monthly credits instead of daily limits
8. Resolution Too High
Error: "Image exceeds maximum pixel count"
Cause: Your image exceeds 100 megapixels.
Solutions:
- Downscale the image before uploading
- For gigapixel images, contact support for options
Still Having Issues?
If your file is rejected for a reason not listed here:
- Check the exact error message in the upload UI
- Verify your file opens in other applications
- Try a different file to isolate the issue
- Contact support with the error details