An online LaTeX editor that's easy to use. Backslash used in wrong place: Another cause of an Undefined Control Sequence error is a backslash used. 649kz9zehmw.tk: Invalid control sequence. If this question can be reworded to fit the rules in the help center, please edit the question. 2. You might try to save the file with another editor which won't add this mark in the try getting rid of \usepackage[dvips]{epsfig,psfrag} if you're using pdflatex. Since updating my miktex packages I get for (even for very Simple files, see MWE ) the Government health card · Lucky man project pumpin radio edit zippy input files through miktex-tex (miktex- pdftex) in turn until all cross-references are trying to compile documents, that is, “649kz9zehmw.tk: Invalid control sequence”. where is etex, latex, pdfetex, pdflatex, pdftex and tex to I never saw an " invalid control sequence" error and I have a lot of doubts.