Install plugin, update plugins or update translate : error -1

Hello,

Can I ask you for help or suggestion. Since few days I can’t :

• update plugins (5 diffrent plugins)
• update translations
• install new plugins

Error : Update without success :-1 (In polish language: Aktualizacja nie powiod?a si?: -1)

On my web page i see : “Briefly unavailable for scheduled maintenance. Check back in a minute.” On wordpress folder appears .maintenance file.

@ I know how to restore my webside (delete .maintenance file) but next time when i try update result is the same.

Do you have any idea what shall i check / change? Did you have the same issue ?