500 error komento

Hi! I've installed and setup Komento, working beautifully on my site. In the admin section however, I get a 500 error with some of the features, such as when I tried to change settings in configuration - database. When I hit 'save', the 500 error occurs. This has happened with a few other settings also. I've included the URL where this particular error occurred, but as I said, it's not the only one.
Could you help me please?
500 - An error has occurred.
Layout _ not found

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