Yeah, i have this trouble too. Have mor than 400 mods aswell, but they didnt make any troubles earlier.

Please follow the Troubleshooting section in the mod's description or I cannot help you.

I have the same issue

Try opening it up when the game just started, there is a small time window where you can open the mod manager.

Got the same issue here. no idea what's going on.

The black screen is removed by switching to window mode and clicking on the window. At least it helped me.
Also, if you have an error or a black screen after you immediately tried to turn on the mod manager after starting the game, just wait a while after starting the game, several stages of the first launch will pass and you will be able to open the mod manager without problems.

Black Screen Rimworld 1.4 This modlist. Only occurs when trying to bring up the prepatcher menu.

version 1.4.3901 rev238 /version
activeMods
zetrith.prepatcher
brrainz.harmony
ludeon.rimworld
ludeon.rimworld.royalty
sf.grim.reality
ludeon.rimworld.ideology
ludeon.rimworld.biotech
redmattis.betterprerequisites
unlimitedhugs.hugslib
redmattis.fastergenesregrowing
mlie.allmemoriesfade
jecrell.jecstools
torann.arimworldofmagic
all.rom.cla.genes
roolo.almostthere
swablu.ambience
animalfilthdontcare.1trickponyta
fluffy.animaltab
com.bymarcin.architecticons
automatic.autolinks
razor2.3.anotherrimworldmod.autocutblight
falconne.aff
bk.babypaste
mlie.backupgenerators
fluffy.backuppower
iluvsilicon.basicmedicine2
bedrestforfoodpoisoning.1trickponyta
lbmaian.begonemessage
redmattis.betterchildren
redmattis.bettergeneinheritance
madeline.modmismatchformatter
v1024.ebframework
imranfish.xmlextensions
nals.facialanimation
erdelf.humanoidalienraces
redmattis.bigsmall.core
redmattis.heaven
redmattis.morexenos
redmattis.bigsmall
redmattis.bigsmall.simplesize
redmattis.bsslimes
redmattis.undead
redmattis.yokai
twistedpacifist.reasonablecomponents
smashphil.vehicleframework
kentington.saveourship2
adaptive.storage.framework
oskarpotocki.vanillafactionsexpanded.core
vanillaexpanded.achievements
vanillaexpanded.vpsycastse
jaxe.rimhud
vanillaexpanded.skills
frozensnowfox.advancedbionicsexpansion
automatic.bionicicons
syrus.bpansresize
petre27.biotechcapacitorgenes
vanya.tools.blightedalert
fluffy.blueprints
owlchemist.boundarytraining
fyarn.boundedroofbuildtool
uuugggg.buildfrominventory
mlie.cts
brrainz.cameraplus
zal.casualty
void.charactereditor
childrentraitsaffectlearning.mod
owlchemist.cleanpathfinding
mlie.clearthestockpiles
sarge945.combatreadiness
mlie.combatreadinesscheck
comigogames.traders.grim
petetimessix.compacthediffs
thewirelord354.conduitdeconstruct
jdalt.cals
sea.consistentgeneinheritance
8z.cookcarefully
captaingeorge.craftableaicore
sjaak31367.craftablecores
tammybee.cutplantsbeforebuilding
da.cosmeticgenes
caesarv6.damageindicators
mlie.dismisstrader
kb.prioritizeresearch
sl4vp0wer.dominantgene
owlchemist.doorclearance
telardo.dragselect
avilmask.commonsense
dubwise.dubsbreakmod
dubwise.dubsmintminimap
ebsg.framework
ebsg.psychic
ebsg.mechanitor
zal.evacore
cocaine.electricstonecuttingtable
v1024.elitearchotech
kikohi.cybernetic
vat.epoeforked
vanillaexpanded.vfepower
hobbes.bamba.evenmorelinkables
falconne.bwm
uuugggg.tdsbugfixes
uuugggg.tdfindlib
uuugggg.everybodygetsone
fredamabob.everythingisagene
statistno1.evolvedorgansredux
erdelf.exportagency
mlie.findagundamnit
fyarn.fixablemooddebuffsalert
kathanon.floatsubmenu
hrg164hjo.vfefuelpipenet.sos2
redmattis.geneextractor
tac.genetrader
avilmask.grazinglands
arandomkiwi.guardsforme
adarafirecaster.hatsarenotclothing
mlie.heatstatistics
rearden.hermaphroditegene
mlie.iclearlyhaveenough
haecriver.injuredcarry
turnovus.biotech.integratedgenes
mlie.justputitoverthere
dhultgren.keepbedownership
mlie.killedenemyautoallowed
asf.deepstorage
mlie.landfill
lewdmora.lewdideologyorigin
brrainz.lineofsightfix
mlie.localgrowingfirst
jecrell.doorsexpanded
avius.locks
espio.losefaith
uuugggg.mealsonwheels
heremeus.mechrechargerstandby
sumghai.medpod
fluffy.medicaltab
fluffy.pharmacist
nunahuralshamikh.medmed
sugarshow.medievalmusic
co.uk.epicguru.meleeanimation
notfood.mendandrecycle
tgo.metaldoesntburn
neronix17.cosmorim.microcommsconsole
zal.mccfix
owlchemist.midsaversaver
velc.mineitall
erdelf.minifyeverything
uuugggg.miningpriority
owlchemist.modulartablesandchairs
owlchemist.moonlight
4loris4.morelinkables
mlie.mountainminer
toxicquokka.movablebiotech
fluffy.musicmanager
hehehew.sexystatue2
oblitus.mylittleplanet
ogre.nanorepairtech
amch.needbaroverflow
voult.betterpawncontrol
brrainz.achtung
mlie.npdtiers
rimfridge.kv.rw
owlchemist.toggleableoverlays
lwm.deepstorage
jangodsoul.simplestorage
netrve.dsgui
zal.nobarrackpenalty
doug.nojobauthors
telardo.nolaggybed
mlie.nomissinggeneicons
dvs.norandomrelations
mlie.noversionwarning
vesper.notmyfault
xenofell.offspringinheritxenogenes
ogre.ogrestack
redundant.oopsallgenepacks
defo.opendoormanually
alias.degeneralizework
mlie.outfitter
owlchemist.owlscolonistbar
peppsen.pmusic
andromeda.packablecontainers
isorex.communityframework
ygdrad.packmulegene
turnovus.submod.backpacksarenotbelts
mlie.pawneducation
jp.perfectpathing
regrowth.botr.core
owlchemist.permeableterrain
vanillaexpanded.vfearchitect
owlchemist.perspectivedoors
owlchemist.perspectiveeaves
mlie.planetarydrill
virathas.plasmashieldimplant
oskarpotocki.vanillaexpanded.ideologypatches
oskarpotocki.vanillaexpanded.royaltypatches
meltup.polyamorybeds.vanilla
ponpeco.pfkidsroom
ponpeco.kidsclothes
puremj.mjrimmods.potentialofyouth
owlchemist.powertab
tk421storm.prioritytreatmentressurected
extracting.organs
erdelf.prisonerransom
mlie.prisonersdonthavekeys
mlie.prisonersshouldfearturrets
longercfloor.proxyheat
avilmask.psychicharmonizerlagfix
lomzie.psychicsensitivitybandwidth
cedaro.psychicimplant
mlie.pulsefireturret
mlie.qualityanddurability
legodude17.qualcolor
hatti.qualitybuilder
hatti.qualitysurgeon
ratys.rtfuse
ratys.rtsolarflareshield
mlie.ra2bunker
regrowth.botr.retextures
vanillaexpanded.vbookse
cedaro.readingbill
mlie.realfactionguest
mlie.realistichumansounds
verniy709.realistichumansounds.androidtierspatch
verniy709.realistichumansounds.harpatch
lucifer.realisticrooms
mlie.recipeicons
bustedbunny.recylethis
redmattis.optimization
rearden.rnh
mlie.relevantstatsindescription
weilbyte.renamecolony
fluffy.fluffybreakdowns
mlie.repairworktype
acruid.repairbench
lts.rh
uuugggg.replacestuff
owlchemist.wallutilities
vanillaexpanded.vfecore
garethp.replacestuffcompatibility
zal.rvpc
thegoofyone.researchassistants
reiquard.researchinfo
avilmask.researchwhatever
somewhereoutinspace.reusepods.updated
rupal.rimpymodmanagerdatabase
arandomkiwi.rimsaves
arandomkiwi.rimthemes
mlie.rimwriter
yrtwof.rimpedia
rimsenal.evp
match.roofsupport
roolo.runandgun
smashphil.srtsexpanded
seohyeon.bestdrugpolicy
owlchemist.scatteredflames
nimrag.scenariosearchbar
mlie.scrollablegenelist
roolo.searchanddestroy
memegoddess.searchanddestroy
tammybee.selectablesculpturegraphic
avilmask.selfdyeing
uuugggg.sharetheload
fox.simplelearning
phaneron.simplelearningretexture
mlie.simplestockpilepresets
owlchemist.ceilingutilities
mlie.simplymorebridges
sins.cuterchildclothes
joseasoler.skipdoordelivery
rabiosus.slimrecharger
despenso.fabbench
despenso.hithechresearchbench
despenso.simpleresearchbench
metalocif.smallergenelab
owlchemist.smartfarming
uuugggg.smartmedicine
puremj.mjrimmods.smartmeditation
rabiosus.smartpistol
sarg.smartspeed
dhultgren.smarterconstruction
legodude17.smartdecon
mlie.smartervisitors
krelinos.socialexpfromtrade
marvinkosh.sometimesraidsgowrong
jaxe.bubbles
jpt.speakup
omgsplat.genesplit
linkolas.stabilize
jelly.stackstufffirst
indeed.stackxxl
dubwise.dubsmintmenus
andromeda.stackgap
fluffytowels.standingcryptosleepcasket
uuugggg.stockpileranking
balistafreak.stopdropandroll
leoltron.storedresearch
simmin.stuffontables
fluffy.stuffedfloors
murmur.subsurfaceconduit
mlie.sustainabledrill
jangodsoul.t45b.powerarmor
treboy.body
rutranickers.notclothingpack
mlie.thebuildwithanythingmod
gt.sam.tilledsoil
mlie.tinyworkbenchs
owlchemist.toggleablereadouts
bazel.toxgen.1
smashphil.dropspot
mlie.tradeableaipersonacore
marvinkosh.ughyougotme
ravinglegend.ultratechcraftingnoneutro
owlchemist.undergroundpowerconduits
uuugggg.usebedrolls
mlie.usethisinstead
nephlite.orbitaltradecolumn
dismarzero.vgp.vgpgardenfabrics
dismarzero.vgp.vgpgardenmedicine
vanillaexpanded.vanillaanimalsexpanded
vanillaexpanded.vaewaste
vanillaexpanded.vappe
vanillaexpanded.varme
vanillaexpanded.basegeneration
sander.vbeautolearn
vanillaexpanded.vfefarming
vanillaexpanded.vfemedical
vanillaexpanded.vfepropsanddecor
vanillaexpanded.ideo.dryads
vanillaexpanded.ideo.iconsandsymbols
vanillaexpanded.vmemese
vanillaexpanded.vnutriente
mrhydralisk.vnpedeepvat
vanillaexpanded.outposts
vanillaexpanded.vanillatradingexpanded
vanillaexpanded.vwenl
vanillaexpanded.vwe
vanillaexpanded.vweq
wvc.sergkart.core
wvc.sergkart.biotech.moremechanoidsworkmodes
murmur.walllight
hauvega.retromod.walltorchesexpandedeasy
zzz.wallvitalsmonitor
mlie.wehadatrader
uuugggg.whatismypurpose
revolus.whatsmissing
co.uk.epicguru.whatsthatmod
tammybee.whereismyweapon
mehni.pickupandhaul
codeoptimist.jobsofopportunity
fluffy.worktab
lordkuper.workmanager
com.yayo.yayoani.continued
lp.levelthisforked
lp.tilledsoilforked
cat2002.showhair
cp.detailed.body.textures.ii
unlimitedhugs.allowtool
fluffy.colonymanager
dubwise.rimatomics
ogliss.ykara.harvesteverything
smuffle.harvestorganspostmortem
haplo.miscellaneous.training
weilbyte.snapout
vanillaexpanded.vchemfuele
vanillaexpanded.vgeneticse
vanillaexpanded.vplantse
vanillaexpanded.vplantsemore
vanillaexpanded.vplantsemushrooms
wvc.sergkart.races.biotech
syrchalis.processor.framework
frozensnowfox.complexjobs
frozensnowfox.filthvanisheswithrainandtime
frozensnowfox.growablegrass
grizzlemethis.tradingspot.rw
calltradeships.kv.rw
vanillaexpanded.vanillatraitsexpanded
moretraitslots.kv.rw
lingluo.movesteamgeyser
nals.dynamicportraits
rh2.cpers.arrest.here
sr.modrimworld.factionalwar
sr.modrimworld.raidextension
syrchalis.glowinghealroot
syrchalis.lightradius
syrchalis.setupcamp
zal.1x1researchtables
mlie.xndprofitableweapons
vanillaexpanded.vfespacer
lmgginspace.repairbed
seobongzu.endlessrecreation

( Adult Mods possibly not steam )

rim.job.world
apf.wearable.♥♥♥♥♥♥♥♥
euclidean.eagleofphantoms.betterrjw
shauaputa.rimnudeworld
c0ffee.rjw.ideologyaddons
otyoty.nudepatchforrimnudeworld.unofficialupdate
akiya82.pregnancystagegraphics
akiya82.nudepatchforrimnudeworld.harpatches
abscon.overt.underwear
abscon.privacy.please
vegapnk.rjw.genes
rjw.sexperience.ideology
c0ffee.rjw.events
c0ffee.rimworld.animations
tory187.rjwanimaddons.voicepatch
tory187.rjwanimaddons.xtraanims
tory187.rjwanimaddons.animalpatch
rjw.♥♥♥
rimworld.ekss.rjwex
rjw.fb
rjw.fh
ed86.rjwia
lustlicentia.rjwlabs
c0ffee.sextoysmasturbation
rjw.sexperience
rjw.milk.humanoid
rjw.menstruation
zulbaljinx.rjw.menstruation.yet.another.retexture
krkr.rocketman

euclidean.s16.core
self.insemination
rjw.sexcultessentials
/activeMods
knownExpansions
ludeon.rimworld
ludeon.rimworld.royalty
ludeon.rimworld.ideology
ludeon.rimworld.biotech
/knownExpansions
/ModsConfigData