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iOS Synchronization

During the synchronization, the App downloads new tasks and forms published for you at the Portal and sends the data collected from your device to the server.

Sync is triggered automatically when you log into your account for the first time.

You can also sync anytime by tapping the Synchronize button at the bottom of the screen. 

Synchronization stages

There are 3 synchronization stages. During synchronization, the dialog appears, informing you of the progress and describing a current stage.

  1. Uploading (only if there are changes to be uploaded)

  2. Updating Settings;

  3. Downloading;

When you perform the synchronization from your app, you will not be able to access tasks and forms as they will be greyed out and marked:


Once you have successfully synchronized your device, you may disconnect it from the Internet and start filling out forms and tasks in the offline mode.

  • When you are finished, connect to the Internet and tap the Synchronize button;

  • Click on the Upload all button to upload collected data. You will see how many changes in responses and tasks are to be uploaded;

Alternatively, you may upload changes to individual responses and tasks by tapping the Upload button on a response or a task card. 

Incremental synchronization

By default, all subsequent synchronizations you perform after the first one are incremental.

During the incremental synchronization, the App only downloads new or changed forms, tasks, and data models from the server instead of downloading all the data each time. 

You can Force full sync (reload all data) instead on the Settings page.

Stopping synchronization

In case you need to stop sync or data upload, press the STOP SYNC button on the progress screen:

It will also interrupt the particular data exchange process, and you will have to restart the synchronization next time. 

Synchronization errors

The syncing process may end up with the following:

  • Failure (sync finished with major errors, no data has been overwritten. User may have to resynchronize to continue working);

  • With errors (some form resources or some parts of a data model failed to download. some forms and/or tasks may be outdated. User may need to resynchronize to continue working).

You will be notified if some of the data from your account fail to download during the sync: this includes form, data model, or contact manager-related information. 

If a form, task definition, or a particular task were affected by the sync error, each would be marked with a tag. 

"Some resources failed to download. Try to restart synchronization."



Unknown Error 

The error does not fit into any of the categories below.

HTTP Response errors with unexpected status codes 

These errors indicate there are some form settings issues and/or the server cannot successfully complete a client's request (Server errors: 5xx / Request errors: 4xx).

Response decoding errors

These errors may occur when the app fails to decode received data because of a conflicting or unsupported data set on the server. In rare cases, it also might happen due to the server update or rollback that revolves around breaking API changes, so either older or newer versions of the app will fail to decode receiving data.

Network timeouts

 If you have no or bad Internet connection, after 5 minutes of waiting for the server to respond, you will receive a Network timeouts error.

Database errors 

There errors happen because of a failed attempt to save/read downloaded data to any database, due to inconsistency in received data or issues with database files. 

File system errors

These errors may happen for various reasons when trying to save/copy/move files such as form resources. For example, when the system tries to move a file to a directory that already contains the file with the same name.

No storage space on the device

The error means you have no place to download any data, take pictures, save forms, etc.

Could not allocate memory

This error occurs when a device does not have enough RAM memory.

Troubleshooting the synchronization issues

Some of the resources, such as forms, contact manager, or task definitions (including tasks attached), may fail to download or update during the synchronization. Sometimes the synchronization may end up with errors. That means some form resources or parts of a data model failed to download or some forms and/or tasks may be outdated.

In this case, you will receive a notification:

Click on the Read More button to see a type of error: 

How to Troubleshoot the Synchronization Failure

In case you have received a notification about failure or errors during the sync, we suggest the following:

1. Make sure you are using the latest version of the app.

 This can be confirmed through the Google Play app on your device. If the application is not updated, there will be an Update button.  

2. Make sure you have a stable Internet connection.

  Signal threats or weak Wi-Fi signals can hinder sync/connectivity. You can test by trying to load another program/app to see if it loads quickly or lags.

3. Try to resynchronize to continue working.

The second try may be successful.

4. Do not close the app while syncing.

If the sync is unsuccessful, try syncing without leaving the app (i.e. - do not change screens, leave the app open to run and perform the sync).

5. Complete the Full Sync in the application Settings.

Go to the app settings, click on the ‘Reload all’ button to run the full synchronization while connected to a stable Internet source without minimizing the application.

 In case the issue is with the synchronization, and the above does not help, try to upload responses one by one by clicking the Upload button directly on the response.

6. As a last resort, try deleting and reinstalling the app.

You can try deleting and reinstalling the app as a last resort, and only when all data has been successfully uploaded.

 If enabling the Force Full Sync option does not help, try deleting and reinstalling the app.

This must not be done while there is any data that has not yet been uploaded, as it will be lost.

Troubleshooting the Server not Found Issue

This warning may appear when the URL is entered with a slash (/) at the end, such as

The iOS apps will immediately warn you that the URL is not supported when there is a slash at the end.

Simply remove the final slash

The issue may also appear for connection issues.

We strongly advise you to perform the synchronization before editing or submitting any information.
 Some of the resources of your forms or tasks could get updated through other instances (for example, the form you need to fill out may be changed from 10 questions to 12 questions and you will be sending an incorrect version).

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