After removing an external data connection (in this case, the spreadsheet was connected to another .xlsm file. The reason is: I'm used to save new versions of the same file to have a manual backup, and in the last version I have copied some data of the previous version and pasted in the last version and, because of it, the Excel created a connection with the previous version. After that, I deleted this connection in data connections menu.) I saved a .xlsm (macro-enabled spreadsheet). After, when I opened it the system ask to repair the file and then reports this message: "Repaired Records: External connections from /xl/connections.xml (Data connection)".
What I have to do to solve this, because the volume of modifications between these versions is too much.