Missing $ inserted in python code

Question

I use python3 (with code not from me) to insert data from a database (bsddb3) from the program GRAMPS into a LaTeX document (TeX Live 2014) and I receive the following error messages:

! Missing $ inserted.
<inserted text> 
                $
l.1131 ...{Foto_Kurt_Neumann"=1 Kurt Neumann 1915}
                                                  %
!  ==> Fatal error occurred, no output PDF file produced!

The relevant part of the python code is:

    self.media_added.add(media_ref.ref)

    path = media_path_full(self.database, media.get_path())
    desc = media.get_description()

    text = ""
    notelist = media.get_note_list()
    for notehandle in notelist:
        note = self.database.get_note_from_handle(notehandle)
        text += le(note.get())

    if intern:
        text += "{\\small\\textit{Bild-ID: %s}}" % (media.get_gramps_id())

    draft_opt = ""
    if draft:
        draft_opt = "draft,"

    tcstar = ''
    if twocolumn:
        tcstar = '*'

    file.write('''%%
    \\begin{figure%s}[tb!p]
    \\raggedright%%
    \\setlength\\fboxrule{.25pt}
    \\setlength\\fboxsep{.25pt}
    \\color{rulecolor}
    \\fbox{%%
    \\setlength{\\imgwidth}{\\linewidth}%%
    \\addtolength{\\imgwidth}{-1pt}%%
    \\includegraphics[%swidth=\\imgwidth,height=1.5\\imgwidth,keepaspectratio]{%s}%%
    }%%
    \\color{textcolor}%%
    \\caption[%s]{%s %s}%%
    \\label{fig:%s}%%
    \\end{figure%s}%%
    ''' % (tcstar, draft_opt, path, le(desc), le(desc), text, media.get_handle(), tcstar))

I have hours trying to solve it now, I do not see where the problem is!?

I tried to add the math mode in \caption:

\\caption[%s]{$%s %s$}%%

But run into an even more crypted (related?) issue, I do not know where it comes from.

Runaway argument?
! Paragraph ended before " was complete.
<to be read again> 
                   \par 

I am totally lost with this error.

Edit

# Latex-Encode
def le(str):
    str = re.sub(r'"\b', r'"', str)
    str = re.sub(r'\b"', r'"', str)
    str = re.sub(r' km\b', r'\\,km', str)
    str = re.sub(r'[\.,!\?]"', r'"', str)
    str = re.sub(r'"', r'"', str)
    str = str.replace("_", "\_")
    str = re.sub(r'(\[[0-9a-e ]+\])', r'\\numberreference{\1}', str)
    str = re.sub(r'(http://[\w\d/\._?&=-]+)',r'\\url{\1}', str)
    str = str.replace('−','--')
    str = str.replace('&','\\&')
    str = str.replace("<u>",'\\rufname{')
    str = str.replace("</u>","}")
    str = str.replace("-)","\"~)")
    str = str.replace("S. ","S.~")
    str = re.sub(r'\)([a-zA-Z])',r')""\1',str)
    str = str.replace("-/","\"~/")
    str = str.replace("-","\"=")
    str = str.replace("/","\\slash{}")
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = re.sub(r'\\url{([^}]*)"=',r'\\url{\1-',str)
    str = re.sub(r'\\url{([^}]*)\\slash{}',r'\\url{\1/',str)
    str = str.replace("#10^00#",'10\\textsuperscript{00}')
    str = str.replace(" #LEBENSLAUF#",'~\\pageref{lebenslauf}')
    return str
    str2 = ''
    for c in str:
        if ord(c)>127:
            str2 += '\mbox{%s}'%c
        else:
            str2 += c
    return str2

Answer 1

The solution is the following. I had to add a line replacing underscores.

str = re.sub(r'"\b', r'\\glqq{}', str)
str = re.sub(r'\b"', r'\\grqq{}', str)
str = re.sub(r'[\.,!\?]"', r'\\grqq{}', str)
str = re.sub(r'"', r'\\textquotedblleft', str)
str = str.replace("_", "\_")  # replaces the underscores, thank to Johannes for point it out!