1.4. Sync issues

If you are unable to perform sync in PDF Expert, there are some steps you can take to troubleshoot the issue.  

First, please make sure you have a stable Internet connection. Try disabling the Wi-Fi, enabling it again, then open PDF Expert > Synced folder > pull down to refresh and trigger the sync process.  

Note: the background sync is not supported for now; you should make sure the app is running to be able to carry out the sync process.

If the sync issue persists, try disconnecting the web storage account from the app and connecting it anew.

To disconnect the storage from the app, follow the steps below:

  • Go to the In the Cloud tab on the sidebar of the PDF Expert app on your iPad (Services tab on the iPhone).
  • Find the storage, tap and hold on it.
  • Tap Remove (if some changes were not synced to the server, save the file's copy locally).

To set up the connection anew:

  • Go to the In the Cloud tab on your device.
  • Tap +Add icon.
  • Choose the needed storage.
  • Sign in again.  

Then, retry to sync your folders again to see if it helps.   

We recommend sending feedback to rdsupport@readdle.com if you have any sync issues. For this, open PDF Expert settings > Support > tap Send feedback. Screenshots illustrating the errors you’re getting (if there are any) will help us see the situation more clearly and assist you.


  • Dropbox sync errors can be caused by the specific copyrighted file if its sharing is restricted by Dropbox copyright policy.

If you sync a file and its sharing is restricted by Dropbox copyright policy, you will see an exclamation mark on the folder and a Restricted content error on the file thumbnail. Remove the file from the folder to get rid of the error message.

  • Some cloud services impose special characters restrictions for the names of files and folders. Using such special characters might lead to sync errors. Please check your cloud service support section for more information on special characters limitation, for example:

Invalid file names and file types in OneDrive, OneDrive for Business, and SharePoint

Restrictions and limitations when you sync SharePoint libraries to your computer through OneDrive for Business

If restricted characters are used in the titles of files and folders, you will see an exclamation mark on the folder  and an unknown error on the file thumbnail:

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