Hearts of Iron 4 Update 1.9.3 Patch Notes (June 4, 2020)

Hearts of Iron IV update 1.9.3 for PC patch notes (June 4, 2020) is now available for players. According to the official patch notes, the new update added brings various bug fixes and gameplay changes. Apart from this, the latest patch also includes various stability and performance improvements.

Recently, a big update was released with various bug fixes. Unfortunately, since the last update, many players were experiencing a number of issues when trying to play.

Read more details here.

What is new in Hearts of Iron IV update 1.9.3 Patch Notes (June 4, 2020)?


  • Decreased suppression value of SP-Art battalions.
  • Decreased suppression value of SP-AA battalions.
  • Decreased suppression value of SP-AT battalions.
  • Decreased research cost on destroyer hulls.
  • Decreased research cost on depth charge technologies.
  • Increased research cost on 1940 and 1944 submarine hulls.
  • Increased research cost on torpedo module upgrades.
  • Decreased research cost of naval munitions upgrades for light and heavy guns.
  • Decreased research cost of armor schemes.
  • Increased the cost of initial radar tech, lowered cost on all other radar techs.
  • Decreased IC cost of all ship heavy batteries.
  • Increased damage of all heavy ship batteries.
  • Increased piercing of all medium ship batteries.
  • Increased damage of all medium ship batteries.
  • Carrier planes no longer take area coverage penalties on their targeted/ground missions.
  • Increased carrier hull surface detection base from 20 to 26.
  • Added a cooldown timer after naval transfers are engaged at sea and escape to avoid stun-locking issues with many small fleets. The cooldown depends on the screening efficiency of the defenders so a defended convoy will have a longer cooldown the better defended it is.
  • Added an extra speed boost to convoys retreat speed when screened.
  • Effective carrier plane advantage in naval combat now gives penalties to positioning for the other side.
  • Increased air-to-air damage factor in carrier battles from 5 to 6.
  • Increase air attack targeting scoring for carriers to make them more likely targets for other carriers.
  • Increased naval hit penalty from 10% to 20% in heavy rain.
  • Reduced carrier traffic penalty from 100% to 80% in heavy rain.
  • Reduce heavy gun target signature from 90 to 80 and increased light gun target signature from 40 to 45 to make heavy guns a bit more versatile and light guns a bit slower at picking off screens.
  • Patrol convoy raiding and convoy escort missions now rely on local navy position for air superiority rather than average of air zones to stop high air superiority in a zone from saving the ships from spotting in another.

Stability & Performance

  • Fixed OOS related to asking an operative to resume their mission after the operation they are assigned to completes.
  • Fixed OOS linked to technologies not being properly reset between games.
  • Fixed OOS triggered by a country asking for manpower after a civil war.
  • Prevented crash when trying to respond to faction invite from a faction that no longer exists.
  • Fixed a ctd that happens when a non-existing capitulated country checks for uncapitulation.


  • Added play_song and scoped_play_song effects.
  • Added on_war_relation_added on action (scope is attacker, from is defender).
  • Made targeting weights for air-to-ship in naval combat moddable. See NAVAL_COMBAT_AIR_*_TARGET_SCORE defines.


  • Updated the forum link in main menu to match the new forum.
  • Bulgaria will no longer start with Flexible Navy focus completed in 1939.
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