Troubleshooting Uploads to Box

If you are having trouble uploading files or folders, please try the following troubleshooting steps:

  • Try clearing your browser's cache. If this does not resolve your issue please proceed to the next step.
  • If you are using the Upload Folders feature, you must have Java installed on your computer, except for Chrome and Firefox which use HTML5 instead of Java to upload folders.
  • Verify that you are using one of our recommended operating systems.
  • Verify that the file's name is valid. Box only supports file or folder names that are 255 characters or less. File names containing non-printable ascii, "/" or "\", names with leading or trailing spaces, and the special names “.” and “..” are also unsupported.
  • Make sure you are uploading files smaller than the maximum for your account type. To determine your maximum, click the arrow next to your name in the upper right-hand corner of your screen and select Account Settings. Then, click on Account and your Max file size will be listed under Account Information.
  • Try uploading using the Upload Files method instead of Upload Folders', or vice versa.
  • Please ensure your web browser is the latest version of Internet Explorer, Safari, Firefox or Chrome.
  • Check to see if you are running the latest versions of Java and Flash.
  • Clear your Java Cache. Follow steps here:
  • Disable any browser plug-ins or add-ons that could be interfering with JavaScript or Java (i.e. NoScript, AdBlock)
  • Check your network connection to Box. If connected to the internet with a wireless card, check to see if the connection to the internet drops intermittently. If this is the case, we recommend the Upload Folders method.
  • Try temporarily disabling or configuring your firewall to allow Box as a trusted site. You may find that your anti-virus software includes a built-in firewall. If you are attempting to access Box from an office setting and experience upload issues, then please contact your IT administrator or internal Help Desk.
  • Proxy servers may sometimes cause failed uploads. If you see the error message: An error occurred with the upload. Please refresh the page and try again. Please contact your IT department or Help Desk and ask them to check your Java security settings or proxy configuration.
  • Restart your computer. Occasionally, one-time issues may prevent Java from functioning correctly, and a restart may solve these problems. Make sure to Allow the Drag and Drop applet once you restart and attempt the upload again.
  • Box Accelerator is a global data transfer network that improves the speed of your uploads. If you are having issues with uploads try turning this off temporarily:
    • Go to Account Settings and click the Sharing tab along the top. Select/deselect the Enable Box Accelerator option under Uploading Content. Click Save.
    • We recommend leaving the Enable Box Accelerator option checked since slowness is usually a temporary network condition that will clear itself.


Potential Causes of Slow Uploads:

Slow upload speeds can have a variety of causes.


Box does not limit, throttle, cap, or shape upload bandwidth for individual files.

Box does perform processing on each file which can impact the total time it takes to complete an upload, particularly when uploading multiple files. But this does not limit the bits/second of your machine's connection to Box.

For more details please read our Fair Use Policy.

If you find that your upload is taking longer than it should, we have listed a few reasons that may affect upload speeds.

  • Firewalls: Firewalls can slow down or block the upload process. If you use third-party software, try temporarily turning off firewalls such as ZoneAlarm, the built-in Windows or Mac firewall, or any others.
  • Business network restrictions: Users accessing Box from an office setting may find that their IT department has blocked or slowed down connections to Box.
    • Try consulting your IT department on restrictions they may have placed on uploads or unapproved web sites.
    • You can determine this by leaving your company network (ex. try a coffeeshop with WiFi) and seeing if the issue persists.
    • VPNs may cause your IP address to be misplaced and inadvertently place your computer in another geographic location other than your actual location. This can affect your upload speeds. Ask your network / IT department if a VPN could be changing your actual location on the internet.
  • Choosing an Upload Method: If you are having an issue uploading, we suggest you try another one of the 3 methods. When you click on the Upload button in your Box account, you should see two links in the pop-up window: Upload Files and Upload Folders.
    • If you click on the Upload Files feature you will use our Multiput/HTML5 (or Flash-based) upload tool, which we recommend for fewer, smaller files.
    • We recommend Upload Folders, a Java-based upload tool, for larger files, folders or a larger number of files. Note: Chrome and Firefox work with Upload Folders but do not need Java.
  • Browser Specific Issues: Try a different browser or computer. Users may find that their upload speeds increase on alternative browsers.
  • Device Specific Issues: If your upload speed has not improved after you have tried updating and/or switching internet browsers, please try a different computer to help isolate the issue.
    • If your upload speed increases on another computer, then you will know that the first computer itself was causing the slower speed.
    • If your speed does not increase, then this is most likely an issue with your internet connection.
  • Internet Service Provider: Sometimes slow upload speeds are the fault of your Internet Service Provider.
    • We recommend a high speed internet connection with high upload speeds.
    • Often with Cable and DSL, the upload speed is significantly slower than the download speed. This will result in fast loading times for most websites and file downloads, but slow uploads.

A Note on Kilobytes vs. Kilobits:

There is a difference between “Kb” (kilobit) and “KB” (kilobyte). One kilobyte is equal to eight kilobits. Internet service providers (ISP) often calculate and advertise upload and download speeds in terms of “Kbps” (kilobits per second) while Box uploads are calculated in terms of “KBps” (kilobytes per second). Therefore, if you are seeing browser upload speeds of 30 KBps this would be interpreted as 240 Kbps by your ISP.


Bandwidth and the Box Accelerator:

Upload speed depends on your network connection and a component of this is bandwidth.

  • Bandwidth allowance determines the amount of data that can pass from the Internet to your web browser in a given amount of time.
  • A smaller bandwidth results in a longer time that it takes Internet data to transfer on your web browser. 

For business and enterprise accounts, Box has proprietary accelerator nodes that allow us to route your uploads through the fastest network route. To kick-start this feature, we suggest uploading approximately 14 files (between 2 and 6MB each) to your account, to initialize the accelerator node’s search for the best route. From there on out, your connection will route your 100MB+ filesize uploads through the fastest route to Box. It takes only a handful of uploads per week to keep the Box Accelerator optimally tuned for your whole office.


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Revision #:
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Last update:
‎06-04-2019 02:25 PM
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