Localhost Gives Error: HTTP ERROR: 503 SERVICE_UNAVAILABLE

[poorlex]

<-------------------------Subsonic Help Request---------------------->
Problem Description: I can't access subsonic via http://localhost:4040 and receive HTTP ERROR: 503 request URI on my Windows 10 PC.
Troubleshooting Steps: I have uninstalled and reinstalled Subsonic; checked Java version, uninstalled and reinstalled Java (old version and new version both 1.8.0_341-b10); still have same issue.
Playback Application and version: Windows 10, clicking "Server Address http://localhost:4040" URL in Subsonic Control Panel, using Firefox 104.0.1 (64-bit)
Subsonic Version: I cannot access the web interface at all due to 503 error. When I installed from Subsonic website I used subsonic-6.1.6-setup file
Version: I cannot access the web interface at all due to 503 error.
Hardware Platform:
Edition: Windows 10 Home 64-bit
Processor: 2x Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz 2.60 GHz
RAM: 128 GB
System Type: 64-bit operating system, x64-based processor
Version: 21H2
OS build: 19044.1889
Java Memory Limit: 150 MB
Problem Filename: N/A
Output from ffmpeg -i: ffmpeg -i is not available in Windows 10 Command Prompt
Last ten log file lines: I cannot access the web interface at all due to 503 error.
<-------------------------Subsonic Help Request---------------------->

[jay_uk]

Linux Mint user here. Same issue for me as of today.

[wayneb64]

I am trying to install on three different PCs, one worked miraculously, the other two I cannot get to login even with fresh install, keep getting the 503 error.