Free tools Windows power users keep installed
One-click scans. No signup required.
The message usually means RuneLite’s launcher could not download or verify the bootstrap files it needs before the game opens. It does not, by itself, mean your RuneLite installation is permanently broken. Check the exact entry in launcher.log, then apply the fix for that error: a timeout points to network or firewall access, HTTP 403 to an upstream block, signature errors to modified traffic, and PKIX/TLS errors to certificate interception.
Try these checks first
- Close every RuneLite window.
- Confirm that your computer’s date, time and time zone are correct. A badly wrong clock can invalidate TLS certificates; this is also reported by users in the community (community report).
- Restart the computer and router.
- Disconnect from a VPN or proxy temporarily.
- Try starting RuneLite through a phone hotspot. If it works there, investigate your normal network, router, DNS filtering or ISP route instead of repeatedly reinstalling.
- Check antivirus, endpoint-security and web-filtering software for HTTPS inspection or a blocked RuneLite executable.
- Read
launcher.logbefore deleting files.
RuneLite’s official troubleshooting guide maps common log messages to likely causes: Troubleshooting problems with the client.
What the fatal download error means
The launcher runs before the game client. It contacts RuneLite’s servers for startup information and update files; if those files cannot be downloaded, are altered in transit or fail certificate verification, the launcher stops with a fatal error.
Bootstrap failure versus gamepack failure
- Bootstrap download: the launcher cannot obtain its startup data, so RuneLite does not get as far as opening the client.
Error loading RS!: RuneLite has progressed further but cannot download the vanilla Old School RuneScape client from Jagex. A socket timeout commonly indicates a slow or unstable connection.- Client startup failure: downloads completed, but Java, graphics, plugins or local configuration prevent the client from running.
These paths need different fixes. Do not treat every “fatal error” as a Java problem or assume reinstalling will repair a blocked connection.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
- HERO Gaming Sensor: Next generation HERO mouse sensor delivers precision tracking up to 25600 DPI with zero smoothing, filtering or acceleration
- 11 programmable buttons and dual mode hyper-fast scroll wheel: The Logitech wired gaming mouse gives you fully customizable control over your gameplay
- Adjustable weights: Match your playing style. Arrange up to five 3.6 g weights for a personalized weight and balance configuration
- LIGHTSYNC technology: Logitech G LIGHTSYNC technology provides fully customizable RGB lighting that can also synchronize with your gaming (requires Logitech Gaming Software)
- Mechanical Switch Button Tensioning: A metal spring tensioning system and metal pivot hinges are built into left and right computer gaming mouse buttons for a crisp, clean click feel with rapid click feedback
Find the exact error in RuneLite’s log
Log locations
- Windows:
%userprofile%.runelitelogs - macOS and Linux:
$HOME/.runelite/logs
On Windows, press Windows key + R, enter %userprofile%.runelitelogs, press Enter, and open the newest launcher.log. Use client.log when the problem occurs after the client or gamepack begins loading. Search for Exception, ERROR:, error fetching bootstrap, timeout, or the messages listed below. If you ask for help, redact usernames, local paths, tokens and other identifying information before sharing a log.
Fix the problem identified by the log
| Log entry | Likely cause | First action |
|---|---|---|
ConnectException: Connection timed out |
Firewall, router or DNS filtering, VPN routing, unstable connection | Try another network, then allow RuneLite through the firewall |
HTTP response code: 403 |
An upstream service or protection layer refused the request | Change networks; test a VPN only where permitted |
SignatureException: Signature length not correct: got 0 but was expecting 512 |
A router, proxy or security product changed the response | Test without traffic inspection, VPN or proxy |
SSLHandshakeException or PKIX path building failed |
TLS interception, an untrusted root certificate or security software | Check antivirus HTTPS scanning and proxy certificates |
Error loading RS! |
OSRS client download from Jagex timed out or failed | Test the connection and distinguish it from a bootstrap error |
Connection timeout and firewall blocks
On Windows, follow the documented firewall path:
- Open Windows Security.
- Select Firewall & network protection.
- Choose Allow an app through firewall, then Change settings.
- Select Allow another app….
- Browse to RuneLite, commonly under
%localappdata%runelite, add it and select OK.
Do not leave the firewall or antivirus disabled. If a VPN makes the error disappear, adjust its route or split-tunneling rules. RuneLite specifically notes that Mullvad split tunneling can prevent connections and recommends disabling split tunneling for RuneLite. A work, school or public network may require its administrator to change firewall, proxy or certificate policy; do not bypass those controls yourself.
HTTP 403
A 403 means the request was refused by the server or an upstream protection service. It is not proof that your RuneScape account is banned, nor proof that RuneLite is globally offline. The official guide suggests changing networks and, where allowed, trying a VPN; VPN addresses can themselves be blocked. If the block continues, contact the relevant network or Cloudflare support rather than repeatedly reinstalling.
Rank #2
- The next-generation optical HERO sensor delivers incredible performance and up to 10x the power efficiency over previous generations, with 400 IPS precision and up to 12,000 DPI sensitivity
- Ultra-fast LIGHTSPEED wireless technology gives you a lag-free gaming experience, delivering incredible responsiveness and reliability with 1 ms report rate for competition-level performance
- G305 wireless mouse boasts an incredible 250 hours of continuous gameplay on just 1 AA battery; switch to Endurance mode via Logitech G HUB software and extend battery life up to 9 months
- Wireless does not have to mean heavy, G305 lightweight mouse provides high maneuverability coming in at only 3.4 oz thanks to efficient lightweight mechanical design and ultra-efficient battery usage
- The durable, compact design with built-in nano receiver storage makes G305 not just a great portable desktop mouse, but also a great laptop travel companion, use with a gaming laptop and play anywhere
Signature errors
The signature-length error indicates that an intermediary may have replaced or modified the downloaded data. Test from a phone hotspot, turn off router traffic rewriting, and temporarily disable narrowly scoped antivirus HTTPS scanning or corporate proxy inspection. Re-enable protection after the test and create an exception only through your security product’s normal controls.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →TLS and certificate errors
For PKIX path building failed or another SSLHandshakeException, inspect antivirus HTTPS scanning, proxy software and installed root certificates. A managed computer may need its administrator to correct the certificate chain.
RuneLite documents a launcher option named Disable TLS verification, corresponding to --insecure-skip-tls-verification, in its launcher configuration guide. This disables certificate verification and is only a short diagnostic test. It is not a permanent repair; restore normal verification immediately afterward, and never use it to justify downloading RuneLite from an unofficial site.
Rank #3
- Pentakill, 5 DPI Levels - Geared with 5 redefinable DPI levels (default as: 500/1000/2000/3000/4000), easy to switch between different game needs. Dedicated demand of DPI options between 500-8000 is also available to be processed by software.
- Any Button is Reassignable - 11 programmable buttons are all editable with customizable tactical keybinds in whatever game or work you are engaging. 1 rapid fire + 2 side macro buttons offer you a better gaming and working experience.
- Comfort Grip with Details - The skin-friendly frosted coating is the main comfort grip of the mouse surface, which offers you the most enjoyable fingerprint-free tactility. The left side equipped with rubber texture strengthened the friction and made the mouse easier to control.
- 5 Decent Backlit Modes - Turn the backlit on and make some kills in your gaming battlefield. The hyped dynamic RGB backlit vibe will never let you down when decorating your gaming space, it would be better with other Redragon accessories with lights on.
- Fatigue Killer with Ergonomic Design - Solid frame with a streamlined and general claw-grip design offers a satisfying and comfortable gaming experience with less fatigue even though after hours of use.
Error loading RS! and Jagex downloads
This message concerns obtaining the OSRS client from Jagex rather than RuneLite’s bootstrap. Test a normal browser connection, restart the router, try another network and temporarily remove VPN or proxy filtering. Check for a Jagex service outage before changing local files. Avoid random downloadable JAR files. Historical advice about replacing vanilla.cache is version-sensitive and should not be used unless current official documentation gives the exact source and procedure.
Clear only the disposable cache
A stale or unwritable cache can prevent updates, but deleting the whole RuneLite directory can remove settings and user data. The official cache locations are:
- Windows:
%userprofile%.runelitecache - macOS/Linux:
$HOME/.runelite/cache
- Close RuneLite.
- Open
%userprofile%.runelite(or~/.runeliteon macOS/Linux). - Rename
cachetocache.oldrather than deleting it immediately. - Launch RuneLite and let it rebuild the cache.
- Delete
cache.oldonly after confirming the client works.
Keep the logs for diagnosis, and back up settings, profiles and screenshots before any broader cleanup.
Rank #4
- ICONIC ERGONOMIC DESIGN WITH THUMB REST — PC gaming mouse favored by millions worldwide with a form factor that perfectly supports the hand while its buttons are optimally positioned for quick and easy access
- 11 PROGRAMMABLE BUTTONS — Assign macros and secondary functions across 11 programmable buttons to execute essential actions like push-to-talk, ping, and more
- HYPERSCROLL TILT WHEEL — Speed through content with a scroll wheel that free-spins until its stopped or switch to tactile mode for more precision and satisfying feedback that’s ideal for cycling through weapons or skills
- 11 RAZER CHROMA RGB LIGHTING ZONES — Customize each zone from over 16.8 million colors and countless lighting effects, all while it reacts dynamically with over 150 Chroma integrated games
- OPTICAL MOUSE SWITCHES GEN 2 — With zero unintended misclicks these switches provide crisp, responsive execution at a blistering 0.2ms actuation speed for up to 70 million clicks
Update or reinstall safely
Reinstallation replaces a damaged or outdated launcher, but it cannot repair a blocked route, proxy or certificate interceptor. Download the installer only from the official page: https://runelite.net/download. Close RuneLite, run the installer for your operating system, start it again and inspect the new log if the same error remains. The project source is available at https://github.com/runelite/runelite; beware of look-alike download pages and modified installers.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Launcher options for targeted diagnosis
Windows provides a RuneLite (configure) Start-menu entry. On macOS and Linux, run:
/Applications/RuneLite.app/Contents/MacOS/RuneLite --configureThe documented options include:
--debug— produce more detailed logging.--nodiff— download full update artifacts instead of differential patches; useful for a corrupt patch, not for DNS, firewall or TLS failures.--noupdate— disable launcher self-updating for a controlled test.--safe-mode— disable Plugin Hub plugins and the core GPU plugin.--insecure-skip-tls-verification— diagnostic-only certificate bypass.--profile=<profile_name>,--scale=<VALUE>and--hw-accel=<OPTION>— configuration controls.
Safe mode is for crashes, freezes or graphics problems after downloads succeed. It usually cannot fix a launcher that cannot fetch its bootstrap. RuneLite’s FAQ describes the safe-mode shortcut and its plugin/GPU scope: RuneLite FAQ.
Best Value
- Professional Gaming Mouse - Redragon M908 optical gaming mouse is designed with up to 12400 DPI, 5 adjustable DPI levels (500/1000/2000/3000/6200 DPI) meet your multiple needs, either for daily work or gaming. DPI can be adjusted freely by ±100 from 200 to 12400 via software. 1000 Hz polling rate, 30G acceleration and high-precision Pixart PAW3327 Sensor giving you a greater edge over your competition.
- RGB Backlight & Programmable Buttons - 16.8 million RGB LED color options (LED Backlight can be disabled). 18 programmable buttons, 5 memory profiles each with a dedicated light color for quick identification. Comes with 8-piece weight tuning set (2.4g x8), easy to change the weight to suit your games.
- Comfort & Precision At Your Hands - Redragon M908 gaming mouse is an essential computer accessory for die-hard with its aggressive design for hands! You will be amazed by the unmatched comfort, lethal accuracy and killer precision of our durable, desktop and laptop pro gaming mouse!
- High-end Design - Redragon M908 Mouse features 6 buttons and 12 MMO programmable side buttons. Durable smooth TEFLON feet pads for ultimate gaming control. 6ft braided-fiber cable with gold-plated USB connector ensures greater durability.
- Die-hard Players Choice - Whether you are targeting, aiming, slashing or attacking, a professional gaming mouse is your basic weapon! The mouse will be your ideal partner. Compatible with Windows 2000/ME/XP/03/VISTA/7/8/10 system for programmable using and Mac OS for normal using.
Use the result of the network test
It works on a hotspot
Focus on the original router, DNS filter, parental-control service, ISP route, firewall or VPN. Keep the working hotspot result as evidence when contacting your ISP or network administrator.
It fails on every network
Prioritize local antivirus or endpoint security, the system clock, a damaged cache, an outdated launcher, TLS interception and permissions. Also check environment variables such as JAVA_OPTS, which RuneLite’s troubleshooting guide notes can prevent launching.
It is a managed computer
If you cannot change firewall rules, root certificates, proxy settings or installation permissions, contact the administrator. Do not weaken enterprise security controls or use a TLS bypass to evade them.
When to seek help
Provide the operating system, RuneLite launcher version, exact error line from launcher.log, whether a phone hotspot works, and whether a VPN or antivirus test changed the result. Remove personal information before posting. This evidence lets support distinguish a network refusal from a damaged cache, TLS interception or an OSRS/Jagex download timeout.
The Bottom Line
Start with the log, not a blanket reinstall: test the clock and connection, isolate VPN/firewall/security software, preserve your settings, and use only the official RuneLite download. Apply risky options such as --insecure-skip-tls-verification only briefly for diagnosis.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
