我在使用这段代码时遇到一个奇怪的错误，但我不知道为什么：
! Text line contains an invalid character.
l.45 ^^@
^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^@^^...
A funny symbol that I can't read has just been input.
Continue, and I'll forget that it ever happened.
我已经尝试删除辅助文件，但这没有帮助。我找不到可能导致此错误的字符。
\documentclass[12pt,a4]{report}
\usepackage{lipsum}
\usepackage[margin=2cm,left=2.5cm,right=1.5cm,includefoot]{geometry} % defines margin of all pages of the thesis
\usepackage[onehalfspacing]{setspace} % sets the line spacing to one and a half
\usepackage{hyperref}
\usepackage[final]{graphicx}
\usepackage{subcaption} % for multiple figures in one figure tab
\listfiles
\usepackage{float}
\usepackage[toc,page]{appendix}
\usepackage{titlesec} %for subsubsub sections
\setcounter{secnumdepth}{4}
\titleformat{\paragraph}
{\normalfont\normalsize\bfseries}{\theparagraph}{1em}{}
\titlespacing*{\paragraph}
{0pt}{3.25ex plus 1ex minus .2ex}{1.5ex plus .2ex}
\usepackage{amsmath} % needed for mathematical symbols like °C
\usepackage{siunitx}
\usepackage{bm} %enables to make math bolf faced
\usepackage{longtable}
\usepackage{booktabs}
\begin{document}
\begin{table}[htbp]
\centering
\caption{Add caption}
\begin{tabular}{rrrrrrrrrrr}
\toprule
Sample & Humidity & Solvent & Concentration & Distance & Feedrate & Voltage & Volume & Molecular Weight & Date & comments \\
\midrule
& & & [wt \%] & [cm] & [$\mu$l/min] & [kv] & [ml] & & & \\
1 & 40 & 2 DMAC :3 Acetone & 20 & 11 & 6 & 26.5 & & 530,000 & 16.10.2015 & \\
2 & 40 & 2 DMAC :3 Acetone & 20 & 14 & 10 & 26.5 & & 530,000 & 16.10.2015 & \\
3 & 40 & 2 DMAC :3 Acetone & 20 & 20 & 10 & 26.5 & & 530,000 & 16.10.2015 & \\
4 & 40 & 2 DMAC :3 Acetone & 20 & 23 & 80 & 25 & & 530,000 & 16.10.2015 & \\
5 & 40 & 2 DMAC :3 Acetone & 20 & 12 & 3 & 18 & & 530,000 & 22.10.2015 & \\
6 & 50 & 7 DMF : 3 Acetone & 17 & 10 & 3 & 20 & & 530,000 & 23.10.2015 & PVDF turned yellow/ degraded, maybe temperature was too high \\
7 & 50 & 7 DMF : 3 Acetone & 17 & 10 & 3 & 21 & & 530,000 & 23.10.2015 & PVDF turned yellow/ degraded, maybe temperature was too high \\
8 & 50 & 2 DMAC :3 Acetone & 15 & 10 & 3 & s & & 530,000 & 27.10.2015 & \\
9 & 49 & 2 DMAC :3 Acetone & 20 & 13 & 6 & 24 & & 530,000 & 29.10.2015 & \\
10 & 49 & 2 DMAC :3 Acetone & 20 & 15 & 6 & 24 & & 530,000 & 29.10.2015 & \\
11 & 55 & 2 DMAC :3 Acetone & 20 & 18 & 6 & 20 & & 530,000 & 30.10.2015 & \\
12 & 55 & 2 DMAC :3 Acetone & 20 & 18 & 6 & 25 & & 530,000 & 30.10.2015 & \\
13 & 50 & 2 DMAC :3 Acetone & 15 & 18 & 8 & 25 & 1 & 530,000 & 4.11.2015 & \\
14 & 50 & 2 DMAC :3 Acetone & 15 & 15 & 8 & 25 & 0.5 & 530,000 & 4.11.2015 & \\
15 & 50 & 3 DMAC :7 Acetone & 15 & 15 & 8 & 25 & 0.5 & 530,000 & 5.11.2015 & \\
16 & 50 & 3 DMAC :7 Acetone & 15 & 15 & 8 & 15 & 0.5 & 530,000 & 5.11.2015 & \\
17 & 50 & 3 DMAC :7 Acetone & 15 & 10 & 8 & 13 & 0.5 & 530,000 & 5.11.2015 & voltage adjusted till i got a stable Taylor's cone \\
18 & 50 & 3 DMAC :7 Acetone & 15 & 18 & 8 & 16 & 1 & 530,000 & 5.11.2015 & voltage adjusted till i got a stable Taylor's cone \\
19 & 55 & 3 DMAC :7 Acetone & 15 & 15 & 8 & 15 & 0.5 & 530,000 & 10.11.2015 & \\
20 & 53 & 3 DMAC :7 Acetone & 15 & 16 & 8 & 15 & 0.5 & 530,000 & 10.11.2015 & \\
21 & 51 & 3 DMAC :7 Acetone & 15 & 16 & 8 & 14 & 0.5 & 530,000 & 10.11.2015 & \\
22 & 46 & 3 DMAC :7 Acetone & 15 & 20 & 8 & 15 & & 530,000 & 12.11.2015 & thick needle \\
23 & 46 & 3 DMAC :7 Acetone & 15 & 17 & 8 & 13 & & 530,000 & 12.11.2015 & thick needle \\
24 & 46 & 3 DMAC :7 Acetone & 15 & 16 & 8 & 12.4 & & 530,000 & 12.11.2015 & thick needle \\
25 & 46 & 3 DMAC :7 Acetone & 15 & 17 & 8 & 13.1 & & 530,000 & 12.11.2015 & \\
26 & 46 & 3 DMAC :7 Acetone & 15 & 16 & 8 & 12.6 & & 530,000 & 12.11.2015 & \\
27 & 46 & 3 DMAC :7 Acetone & 15 & 15 & 8 & & & 530,000 & 12.11.2015 & \\
\bottomrule
\end{tabular}%
\label{tab:addlabel}%
\end{table}%
\end{document}