EDIT:
Well I hope you learned that "simply reinstall everything" is not the best strategy to solve problems. miktex can't create the format file, so you need to find out why. Go to the miktex console, settings -> tab format. Select pdflatex and click on build. If it fails you perhaps get the real log-file. - Ulrike Fischer
After doing this, the build failed, the error message refers to this log initexmf_admin.log:
2018-10-05 02:14:23,267+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:14:23,267+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:14:23,267+0200 INFO initexmf - starting with command line: initexmf --rmfndb --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:14:23,267+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:14:23,670+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:14:23,670+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:14:23,670+0200 INFO initexmf - starting with command line: initexmf --update-fndb --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:14:23,670+0200 INFO initexmf - Skipping user root directory (C:\Users\user\AppData\Roaming\MiKTeX\2.9)... 2018-10-05 02:14:23,670+0200 INFO initexmf - Skipping user root directory (C:\Users\user\AppData\Local\MiKTeX\2.9)... 2018-10-05 02:14:23,670+0200 INFO initexmf - Creating fndb for common root directory (C:\ProgramData\MiKTeX\2.9)... 2018-10-05 02:14:23,717+0200 INFO initexmf - Creating fndb for common root directory (C:\Programme\MiKTeX_2.9)... 2018-10-05 02:14:38,025+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:14:38,344+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:14:38,344+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:14:38,344+0200 INFO initexmf - starting with command line: initexmf --force --mklinks --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:14:38,750+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:14:39,078+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:14:39,078+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:14:39,078+0200 INFO initexmf - starting with command line: initexmf --mkmaps --mklangs --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:14:39,078+0200 INFO initexmf - Creating language.dat, language.dat.lua and language.def... 2018-10-05 02:14:39,141+0200 INFO initexmf - running: mkfntmap --verbose --admin --disable-installer 2018-10-05 02:18:07,080+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:07,395+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:07,395+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:07,395+0200 INFO initexmf - starting with command line: initexmf --default-paper-size=A4 --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:07,442+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:07,754+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:07,754+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:07,754+0200 INFO initexmf - starting with command line: initexmf --set-config-value=[MPM]AutoInstall=1 --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:07,785+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:08,113+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:08,113+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:08,113+0200 INFO initexmf - starting with command line: initexmf --update-fndb --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:08,113+0200 INFO initexmf - Skipping user root directory (C:\Users\user\AppData\Roaming\MiKTeX\2.9)... 2018-10-05 02:18:08,113+0200 INFO initexmf - Skipping user root directory (C:\Users\user\AppData\Local\MiKTeX\2.9)... 2018-10-05 02:18:08,145+0200 INFO initexmf - Creating fndb for common root directory (C:\ProgramData\MiKTeX\2.9)... 2018-10-05 02:18:08,207+0200 INFO initexmf - Creating fndb for common root directory (C:\Programme\MiKTeX_2.9)... 2018-10-05 02:18:22,365+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:22,677+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:22,677+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:22,677+0200 INFO initexmf - starting with command line: initexmf --register-shell-file-types --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:22,724+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:23,096+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:23,096+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:23,096+0200 INFO initexmf - starting with command line: initexmf --modify-path --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:23,269+0200 INFO initexmf - finishing with exit code 0 2018-10-05 02:18:23,597+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 02:18:23,597+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 02:18:23,597+0200 INFO initexmf - starting with command line: initexmf --report --admin --log-file=C:\Programme\MiKTeX_2.9\miktex/config\uninst.log --disable-installer --verbose 2018-10-05 02:18:31,263+0200 INFO initexmf - finishing with exit code 0 2018-10-05 09:03:58,226+0200 INFO initexmf - starting: MiKTeX Configuration Utility 2.9.6811 (MiKTeX 2.9.6840 64-bit) 2018-10-05 09:03:58,226+0200 INFO initexmf - Operating on the shared (system-wide) MiKTeX setup 2018-10-05 09:03:58,226+0200 INFO initexmf - starting with command line: initexmf --admin --dump=pdflatex 2018-10-05 09:03:58,241+0200 INFO initexmf - running: miktex-makefmt.exe --engine=pdftex --dest-name=pdflatex --no-dump pdflatex.ini --engine-option=-tcx=cp227.tcx --admin --enable-installer 2018-10-05 09:03:59,101+0200 ERROR initexmf - sub-process error output has been saved to 'C:\ProgramData\MiKTeX\2.9\miktex\log\miktex-makefmt_2018-10-05-090359.out' 2018-10-05 09:03:59,101+0200 FATAL initexmf - The executed process did not succeed. 2018-10-05 09:03:59,101+0200 FATAL initexmf - Info: fileName="C:\Programme\MiKTeX_2.9\miktex\bin\x64\miktex-makefmt.exe", exitCode="1" 2018-10-05 09:03:59,101+0200 FATAL initexmf - Source: 2018-10-05 09:03:59,101+0200 FATAL initexmf - Line: 0