|   | 1 |  initial version  | 
I can reproduce your problem. It seems that there is somewhere a version mismatch. Indeed, you can try the following command (from your terminal):
find /home/user_name/miniconda3/ -name "libec.so*"
You will see some libec.so.4 not libec.so.3
This should be fixdd upstream, thanks for reporting. A temporary workaround (that might lead to problems somewhere in Sage) is:
cd miniconda3/envs/sage/lib
ln -s libec.so.4.0.0 libec.so.3
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                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.