# Mathematica 11 introduced strange autocomplete bug

today i upgraded from MM 10.4.1 (which run without any problems) to MM 11.

But for me, it introduced a strange autocomplete-bug. When i try to type in "Plot" i get a huge (>5seconds) lag when i come to the second character. After that lag the autocomplete pops up (with a visible build up time [~1 second]). But it gets more strange, when i open the autocomplete for the Plot-command itself to insert the autocomplete patterns Mathematica returns a error. I made a screenshot of it:

But i do not get what the error tells me. Nevertheless i tried to resolve the problem in many ways.

• I tried to delete everything in \$UserDirectory and \$BaseUserDirectory
• I made a soft reset
• I reinstalled Mathematica

Another thing i noticed (what probably also could be a thing from mma11) is that the Preferences-Window takes a significant time to show up (5-10 seconds) (and prior even showing a "formatting notebook" dialog) and also operates with a noticeable lag when switching options.

Mathematica itself runs smoothly when switching the autocomplete off. (Except the Preferences-Window)

• Although I do not encounter any unexpected delays, I can reproduce the error message you obtained. The far left of your image contains PlotPlot, which you obtained when you pasted in the first choice for Plot from the drop-down menu. This is a bug. Mathematica does not behave this way, when you do the same things with, for instance, DSolve. – bbgodfrey Aug 12 '16 at 0:39