Help migrating client from ownCloud

I am trying to migrate from the owncloud client to the nextcloud-beta client on an up-to-date Ubuntu 18.04.1 machine. I do not have admin access to the server. The server is running version 10.0.6. The GUI starts correctly, asks me to authenticate, and then shows me the files on the server. However, it will not sync.

I have a second machine on which I installed the nextcloud-beta client from scratch, with no previous owncloud setup. On that one everything works, including syncing.

The configuration files ($HOME/.config/Nextcloud/nextcloud.cfg) are essentially the same on both machines. However there are some differences in the log files that may be significant. On the machine that will not sync, I have lines like this (using “example.com” to hide my actual domain):

[OCC::AccessManager::createRequest      6 "GET" "https://owncloud.example.com/ocs/v2.php/core/navigation/apps?absolute=true&format=json" has X-Request-ID "32360216-c538-4a74-9288-32d329318855"
[OCC::AbstractNetworkJob::start         OCC::OcsNavigationAppsJob created for "https://owncloud.example.com" + "ocs/v2.php/core/navigation/apps" ""
[OCC::AccessManager::createRequest      6 "GET" "https://owncloud.example.com/ocs/v2.php/core/navigation/apps?absolute=true&format=json" has X-Request-ID "04bf0723-0172-4915-b3af-06edd4ef691c"
[OCC::AbstractNetworkJob::start         OCC::OcsNavigationAppsJob created for "https://owncloud.example.com" + "ocs/v2.php/core/navigation/apps" ""
[OCC::WebFlowCredentials::slotFinished  request finished
[OCC::AbstractNetworkJob::slotFinished  QNetworkReply::NetworkError(ContentNotFoundError) "Server replied \"404 Not Found\" to \"GET https://owncloud.example.com/ocs/v2.php/core/navigation/apps?absolute=true&format=json\"" QVariant(int, 404)

By contrast, on the machine that syncs properly, there are lines like this:

[OCC::AccessManager::createRequest      2 "" "https://owncloud.example.com /ocs/v1.php/cloud/capabilities?format=json" has X-Request-ID "731284f9-4b17-4bb1-b7a7-a3b8482d969f"
[OCC::AbstractNetworkJob::start         OCC::JsonApiJob created for "https://owncloud.example.com" + "ocs/v1.php/cloud/capabilities" "OCC::ConnectionValidator"
[OCC::AccessManager::createRequest      2 "" "https://owncloud.example.com/ocs/v1.php/config?format=json" has X-Request-ID "82d093b8-ddab-4ef6-b9e8-fb149c05506c"
[OCC::AbstractNetworkJob::start         OCC::JsonApiJob created for "https://owncloud.example.com" + "ocs/v1.php/config" ""
[OCC::JsonApiJob::finished      JsonApiJob of QUrl("https://owncloud.example.com/ocs/v1.php/config?format=json") FINISHED WITH STATUS "OK"

I note different request paths involving v1.php on the one that’s working and v2.php on the one that fails with HTTP error code 404. Would it solve my problem to coerce my problematic client installation to use the “v1.php” path? How could this be done?