WooCommerce Update does not download

Download of update to version 2.1.12 from the plugin menu starts, then nothing happens.

“Downloading update from https://downloads.www.ads-software.com/plugin/woocommerce.2.1.12.zip… (translated from German)

And it just stays there. Any ideas?

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I’m afraid to install the whole package of the new version, since all modifications might be lost.