I'm trying to change the width of the abstract with \absleftindent and \absrightindent, using the abstract package. But when compiling the document I get the following error message
I installed the package manually using latex abstract.ins (together with the source file abstract.dtx). Also I was trying to install the package by downloading the abstract.zip from the CTAN directly but still the problem persists in abstract.sty. Someone could help me please, I do not have much knowledge in .ins programming so I have not been able to correct the code on my own.

\documentclasscommand, have a minimal preamble and then\begin{document}...\end{document}. The code should compile and be as small as possible to demonstrate your problem. Cutting your code down to a MWE may well reveal what your problem actually is. In any case, it is really difficult to help you without more information. – Jul 24 '17 at 04:10