how to read some hundreds pdf files with many heavy graphics and tables?

Question

I am trying to import and extract texts from ca 800 pdf files in R. The files have some heavy graphics and tables, which, I guess, are the problems to read the pdf files - When using the commend readtext, R crashes after repeating the error (font invalid weight). I tried with subsets with less files (like 100), but I still cannot extract the texts. Does anyone have similar experiences? Which command should I use, in order to read my pdf files without problems??