Bibliography problem: ! Missing \endgroup inserted

Question

Im trying to get my bib to work. It seems to have a problem with this entry:

@misc{foto:hecke,
 author = {L. Reidemeister},
 title = {Foto: Hecke, Erich},
 url = {https://opc.mfo.de/detail?photo_id=12567},
 note = {[Online; aufgerufen 19 Oktober 2017]}
}

While trying I switched to biblatex hoping it would solve it. This is how my TeX looks:

\documentclass[12pt, a4paper, headsepline]{scrartcl}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}

\usepackage{hyperref}
\usepackage{csquotes}
\usepackage[language=german, style=authoryear, backend=bibtex]{biblatex}
\addbibresource{inhalte/literatur.bib}

\usepackage{caption}
\usepackage[pdftex]{graphicx}
\usepackage{latexsym}
\usepackage{amsmath,amssymb,amsthm}
\usepackage[export]{adjustbox}

\begin{document}
    \paragraph{Erich Hecke} Bla...
    \begin{figure}[h!]
        \centering
        \includegraphics[height=5cm]{bilder/Hecke_E-OPC.jpg}
        \caption*{Hecke, Erich. \cite{foto:hecke}}
        \label{fig:hecke}
    \end{figure}

    \begin{thebibliography}
        \printbibliography
    \end{thebibliography}

\end{document}

The Error message:

[2] (arbeit.tex <bilder/Hecke_E-OPC.jpg, id=29, 270.00874pt x 401.5pt>
<use bilder/Hecke_E-OPC.jpg>) [3 <./bilder/Hecke_E-OPC.jpg>] [4]
! Missing \endgroup inserted.
<inserted text> 
                \endgroup 
l.71        \printbibliography

already tried to escape the url, or use different styles :( Thanks in advance!

Answer 1

\printbibliography does not need to be wrapped into a thebibliography environment. thebibliography is used by manual bibliographies and BibTeX. biblatex has its own environment which is automatically called by \printbibliography.

You need to replace

\begin{thebibliography}
  \printbibliography
\end{thebibliography}

with

\printbibliography