As of May 2025, Fail to communicate with server (500) may occur during app login if there is a mistake in entering the account string (company ID), or if the account string concerned has been suspended or deleted. If this applies to you, please refer to this article.
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Communication with the server has not been established.Perform the following operation.
・Check the communication environment and line and then log in again with no restrictions in a network environment using a 3G/4G/LTE/Wi-Fi line.
・Appears in response to a login trial from a device that is not specified in the contract.In this case, ask your administrator to change the service.
・Appears when an iPhone application has been installed on an iPad device.Delete the app, install an iPad app, and then log in again.