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ACE COMBAT 8

ACE COMBAT 8 Error ST-3100001 on PC: Check Windows Time Synchronization

For the Steam version of ACE COMBAT ONLINE showing ST-3100001 during play or deployment and preventing you from continuing. Guidance and notices were checked for the Japanese article on October 2, 2026.

Edited by Gemnao Editorial Team (Japanese)Last checked 2026-10-02
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The short answer

The publisher describes ST-3100001 as a general error shown when communication with the game server is lost. Its recommended first check is whether Windows time is incorrect. Open Settings → Time & language → Date & time → Sync now, then restart Steam and the game. This error code does not identify a single cause.

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Key facts

Meaning (publisher)
A general error when communication with the game server is lost
Official first check
Check Windows clock accuracy, synchronize it and retry
Synchronize time
Settings → Time & language → Date & time → Sync now
Measure offset (administrator PowerShell)
w32tm /stripchart /computer:time.windows.com /samples:5 /dataonly
Error after a mission
The September 29 official notice said the results-screen issue was being addressed and affected penalties were planned to be removed. Check newer notices.

Find your symptom

Start with your symptom. Skip steps that do not apply to your setup.

What you seeWhat to checkGo to
Matchmaking and aircraft selection work, but deployment repeatedly failsAn incorrect clock is one reported possibility; start with the official synchronization checkStep 1
Sync now fails, or the clock drifts againCheck the Windows Time service and measured offsetStep 2
Disconnects during a match, including in other online gamesInvestigate connection stability and official server noticesStep 3
Error after a mission instead of the results screenCompare with the issue described in the September 29 official noticeStep 3

Fixes, in order

Continue this issue

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Step 1｜Synchronize Windows time: the official first check

Players have reported deployment failures when their PC clocks were off by only a few minutes. These reports do not establish the cause of every occurrence.

Time: About 2 minutes · Risk: low

  1. Press Windows + I → Settings → Time & language → Date & time.
  2. Make sure Set time automatically is on, then choose the correct time zone for your location. The Japanese edition uses Osaka/Sapporo/Tokyo (UTC+09:00) as its local example; readers elsewhere should use their own correct zone.
  3. Under Additional settings, choose Sync now.
  4. Fully close Steam and ACE COMBAT 8, reopen them and try deploying again.

You can also right-click the taskbar clock and choose Adjust date and time.

Step 2｜Measure clock offset and check the synchronization service

Use this when Sync now fails or the issue persists. These are built-in Windows commands, not a downloaded repair tool.

Time: About 5 minutes · Risk: low

  1. Press Windows + X and open Terminal (Admin), accepting the Windows elevation prompt only if you intend to run these commands on your own PC.
  2. Run w32tm /stripchart /computer:time.windows.com /samples:5 /dataonly . Values close to zero, such as +0.02s, show little measured offset; tens of seconds or minutes show a clock discrepancy. This is not a guarantee that the game will connect.
  3. If the time is off, run w32tm /resync /force to request synchronization.
  4. If Windows says the service has not been started, run Start-Service W32Time, then run w32tm /resync /force again.
  5. Repeat the first command to check the offset, then restart Steam and ACE COMBAT 8.

A player in the linked Steam discussion reported an approximately 136-second offset and being able to deploy after correcting it. That is an individual player report. On a managed work or school PC, ask its administrator before changing time-service behavior.

Step 3｜Check official notices and compare the connection

Because this is a general connection-loss error, a correct clock does not rule out a server or connection problem.

Time: About 5 minutes · Risk: low

  1. Check the official ACE COMBAT X account (@PROJECT_ACES) and Steam news for outages and maintenance. Gemnao’s status page is also available in Japanese.
  2. If the error appears after a mission instead of the results screen, compare with the issue in the September 29 notice and look for an official resolution update.
  3. On Wi-Fi, compare a wired connection if available. If appropriate for your own connection, pause a VPN or network-optimization tool for a separate comparison; do not change a managed network’s required settings.
  4. Restart your router when it is safe to interrupt the connection, then retry.

Avoid

  • Repeatedly attempting deployment with the same unresolved error; check time first
  • Leaving the clock manually offset; restore automatic time after checking
  • Using repair tools or scripts from unknown sources

Important cautions

  • In its September 29, 2026 notice, the publisher said it planned to clear penalties caused by the mission-end error. This is a dated plan, not confirmation that a specific account’s penalty has been removed.
  • Do not apply this code’s explanation to another error code without its own official guidance.

FAQ

What does ST-3100001 mean?

The official notice describes a general error when communication with the game server is lost. Causes can differ; the publisher recommends checking Windows time synchronization first.

I received a penalty when the error disconnected me. What happens?

For the error after a mission instead of the results screen, the September 29 notice said the issue was being addressed and affected penalties were planned to be cleared. Check newer official notices; this does not confirm the status of an individual account.

The clock looks correct. Should I still check?

The taskbar clock may not make a difference of a few seconds obvious. Players in the Steam thread reported an offset of a little over two minutes that they had not noticed. The w32tm /stripchart command measures the difference in seconds.

Sources

The code meaning and first clock-sync check come from the publisher’s notice. Clock-offset examples are player reports, not official measurements or a guaranteed fix. The mission-end issue and penalty plan reflect the dated September 29 notice; check for newer official updates.

Official Steam news: ST-3100001, September 30, 2026Official ACE COMBAT X: Mission-end error notice, September 29, 2026Steam Community player reports: I FOUND HOW TO FIX ST-3100001Microsoft Learn: Windows Time service tools and settings, w32tm (Japanese)ACE COMBAT 8 (Japanese)Japanese version of this page