I tried to upgrade via $sage -upgrade and got an error

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Could you please give us some informations so that someone can try to reproduce your problem:

• which version of Sage did you use ?
• which OS ?
• did you install Sage from the binaries, and which ones ?
• did you compile Sage yourself ?
• which command did you type precisely to get the error ?
• which error message did you get ?
• ... ?

For "what to do next?", you can just back up you ~/.sage and then download a fresh copy of sage binary. I do it all the time, simply because it leaves one with a working copy of sage in case anything goes wrong during the upgrade (though it rarely so).