I ran your code (for the second regression) using automatic Stata data. I am not sure what error you are pointing out. I managed to create a pdf file from latex output.
................ Stata strong code> ................
sysuse auto regress mpg foreign weight outreg2 using myfile2, tex(frag) se coefastr symb(***,**,*) rdec(3) bdec(3) r2 nocons append
.......................... latex output ..................
\documentclass[]{article} This is added \begin{document} This is added \begin{tabular}{lcc} \hline & (1) & (2) \\ VARIABLES & mpg & mpg \\ \hline & & \\ foreign & -1.650 & -1.650 \\ & (1.076) & (1.076) \\ weight & -0.00659*** & -0.007*** \\ & (0.000637) & (0.001) \\ Constant & 41.68*** & \\ & (2.166) & \\ & & \\ Observations & 74 & 74 \\ R-squared & 0.663 & 0.663 \\ \hline \multicolumn{3}{c}{ Standard errors in parentheses} \\ \multicolumn{3}{c}{ *** p$<$0.01, ** p$<$0.05, * p$<$0.1} \\ \end{tabular} \end{document} This is added
........................ ...... pdf output from latex output .....

Note : you can remove the append parameter if you do not want the second column to be displayed.
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