Troubleshooting Siemens LOGO! Web Editor 'User Web Page Not Found' Error

Problem Description

When configuring the Siemens LOGO! 8 onboard web server to host a user-defined visualization built with LOGO! Web Editor (LWE), the engineer accesses the LOGO! base web interface successfully (status page, variable view, login prompt) but receives a "User web page not found" message when navigating to the custom project URL. The browser displays either a 404 Not Found HTTP response code or a LOGO!-generated HTML error page carrying the same wording.

This error is produced by the LOGO! HTTP server when it receives a GET request for the entry point of the LWE project - typically index.htm, index.html, or the configured HTML file - but cannot locate the file on the inserted microSD card. The condition is functionally identical to a generic HTTP 404: the resource the client requested is not present at the URL the server is mapping to.

According to the MDN Web Docs HTTP 404 reference, a 404 indicates that the server cannot find the requested resource. In the LOGO! context the response is always a server-side file-not-found condition rooted either in the SD card file system, in the LWE project deployment, or in firmware incompatibility - never in the client browser configuration.

Affected Hardware and Firmware

LWE web server functionality is a hardware-feature of specific LOGO! 8 generations. Identify the base unit part number on the right-side label of the LOGO! module before any troubleshooting step - this is the single highest-value diagnostic action.

The full Siemens ordering designation is structured as 6ED1052-1XX08-0BAY where Y is the firmware revision (0, 1, or 2) and the XX digits encode the variant (e.g., MD for LOGO! 12/24 RCE, CC for LOGO! 230 RCE, BB for LOGO! 24 CE). Confirm the suffix ends in -0BA1 (LOGO! 8.3) or -0BA2 (LOGO! 8.4) before any other action.

For full part-number coverage refer to the Siemens Industry Online Support catalog or the LOGO! 8 system manual. The official LOGO! product page lists the current ordering data, accessories, and the latest firmware revisions.

Root Cause Analysis

Three primary root causes produce the "User web page not found" error. Each is verified independently in the diagnostic procedure below.

1. SD card size or file-system incompatibility. LOGO! 8.3 and 8.4 firmware is rated for microSDHC cards up to 32 GB formatted as FAT32. Field experience shows that older firmware revisions and certain microSDHC controllers fail to enumerate or read cards larger than 4 GB. A 2 GB microSD card formatted as FAT32 is the safest combination and the recommended default for LWE deployment.
2. LWE project not transferred to the SD card. Compiling the project in LOGO! Web Editor only produces output on the engineering PC. The compiled files must be explicitly downloaded to the LOGO!; during download the LOGO! writes them into a project folder on the inserted microSD card. If the SD card is absent, unreadable, or the download step was skipped, the LOGO! has nothing to serve and returns 404 for the user project path.
3. LOGO! base unit does not support LWE. Pre-LOGO! 8.3 hardware (-0BA0) does not have the LWE interpreter embedded in firmware and will not load user web projects under any condition. The error manifests identically regardless of SD card presence and is not user-fixable through configuration.

Secondary causes (less common, but documented):

• Web server access mode disabled in the LOGO! Soft Comfort program configuration (Tools > Ethernet Connections > Web Server Access).
• Browser cache serving a stale 404 from a previous failed attempt - resolved with a hard refresh (Ctrl+Shift+R).
• PC host firewall blocking HTTP traffic on port 80 to the LOGO! IP subnet.
• LWE project image asset exceeds 2 MB and is silently dropped during transfer.

Prerequisites

Resolve the error with the following prerequisites in place:

• LOGO! 8.3 (6ED1052-1xx08-0BA1) or LOGO! 8.4 (6ED1052-1xx08-0BA2) base unit, confirmed by reading the part-number label.
• LOGO! Soft Comfort 8.3 or later installed on the engineering PC. The LWE component is bundled with the LOGO! Soft Comfort installer.
• A microSD card of 2 GB to 4 GB capacity, formatted as FAT32. Avoid SDXC (>32 GB) and cards formatted as exFAT.
• Ethernet connectivity between the PC and the LOGO! base unit - direct cable, switch, or routed LAN.
• Browser on Windows 10/11 (Edge, Chrome, Firefox) for verification. Safari and mobile browsers are acceptable but not the engineering primary.
• Static IP address assigned to the LOGO! (DHCP is supported but a static address is recommended for production visualization).

Diagnostic Procedure

Execute the diagnostic procedure in sequence. Do not skip the part-number verification step - it is the single highest-value action.

1. Identify the LOGO! part number. Power off the LOGO! base unit. Remove the terminal cover. Read the order number printed on the right-side label. Confirm it ends in -0BA1 or -0BA2. If it ends in -0BA0, the LWE web server is not available and no SD card configuration will resolve the 404. Consider a hardware replacement if LWE is a hard requirement.
2. Verify the SD card is detected by the LOGO!. Insert the microSD card fully into the slot on the front of the LOGO! (with the LOGO! powered off). Power on the LOGO!. From the onboard display, navigate using the cursor keys: ESC > Diagnostic > Hardware > SD Card. The screen reports the card manufacturer, capacity, and free space. If "No SD Card" is shown, reseat the card, power-cycle the LOGO!, and confirm the card is fully inserted (click into the socket). If the card is still not detected, substitute a known-good card.
3. Switch the LOGO! to STOP mode. From the onboard display, navigate to ESC > Stop. Confirm the LOGO! is in STOP before initiating the LWE download. Some LOGO! firmware revisions refuse to write to the SD card while the unit is in RUN mode, which produces a silent transfer failure and the resulting 404 at runtime.
4. Transfer the LWE project. In LOGO! Web Editor, open the project. From the menu select Tools > Transfer > Transfer to LOGO! (or click the Transfer button on the toolbar). When prompted, enter the LOGO! IP address and the LOGO! access password (default: LOGO). Wait for the transfer to complete. The progress indicator should reach 100% and report "Transfer completed successfully." The LOGO! writes the HTML, CSS, JavaScript, and image files into a project folder on the microSD card during this step.
5. Return the LOGO! to RUN mode. From the onboard display, navigate to ESC > Start. Alternatively, use LOGO! Soft Comfort online mode and issue the Run command. The LOGO! will read the deployed LWE project from the SD card during the RUN transition and hold it in memory.
6. Access the user web page. Open the browser and navigate to http://<LOGO_IP_address>/. The LOGO! onboard web server should now serve the LWE project as the root document. If the user project was deployed to a subfolder, navigate to http://<LOGO_IP_address>/<project_folder>/. The default LWE project folder is named after the LWE project.
7. Verify HTTP response codes. Open a browser developer console (F12 > Network tab) and reload the user page. Confirm the response code is 200 OK for index.htm and every sub-resource (CSS, JS, PNG, SVG, font). A 404 Not Found on any referenced asset indicates a partial upload and warrants a re-transfer.

LOGO! Onboard Menu Walkthrough

The following is the exact key sequence for the SD card diagnostic path on LOGO! 8.3 / 8.4 firmware. The default screen on power-up is the message text or, with no program loaded, the LOGO! identifier.

If the SD Card screen reports "No SD Card", the LOGO! does not see the card. Re-seat the card, confirm it is a FAT32 / FAT16 format, and substitute a different card if the issue persists. If the screen reports the card capacity but with zero free space, offload the project files and clear the card.

SD Card Compatibility Specification

The LOGO! 8 microSD slot accepts the following card classes, with the documented caveats:

Format the card with the following partition parameters:

• Partition type: MBR (Master Boot Record), not GPT.
• File system: FAT32 (FAT16 acceptable for <2 GB cards).
• Allocation unit size: Default, as selected by the formatter based on card capacity.
• Volume label: Optional, e.g. LOGO_LWE.

On Windows, format with format X: /FS:FAT32 /Q from an elevated command prompt, or use the GUI format dialog and explicitly select FAT32. On Linux, use mkfs.vfat -F 32 /dev/sdX1. Do not use the SD Card Formatter tool with "Logical Size Adjustment" enabled for cards larger than 4 GB - the tool will rewrite the file system to exFAT and the LOGO! will reject the card silently.

LWE Project Upload and Deployment

Deployment consists of two independent operations that must both succeed.

1. Project compilation in LWE. Open the project in LOGO! Web Editor. From the menu select Project > Build (or press F7). The Build output window must report zero errors and zero warnings. Warnings about missing tag bindings will still allow the project to compile but will produce placeholder values at runtime.
2. Project transfer to the LOGO!. With the LOGO! in STOP mode, from LWE select Tools > Transfer to LOGO!. The transfer dialog shows the target IP address. The LOGO! access password defaults to LOGO unless changed in the LOGO! Soft Comfort program. Click Transfer. The progress indicator should advance to 100% and report "Transfer completed successfully."

After successful transfer, the LWE project resides on the microSD card in a folder named after the project. The LOGO! maps the user web root to that folder. To verify the file presence, power off the LOGO!, remove the card, mount it on a PC, and confirm the following file layout (example):

/USERPROJECT/
├── index.htm
├── logo.png
├── style.css
├── app.js
└── variables.json

If index.htm is missing, the LWE transfer did not complete and the LOGO! will return 404 for the root path. If sub-resources are missing, individual assets will 404 but the main page will load with broken styling or missing images.

Transfer Failure Modes

Common reasons for a partial or failed LWE transfer:

• LOGO! was in RUN mode when the transfer was initiated. The LOGO! silently drops the write or rejects the transfer.
• SD card became full during transfer. Free space is consumed by both the LWE project files and the LOGO! data log files.
• Image asset exceeds 2 MB. The LOGO! drops oversized assets without error notification.
• Engineering PC lost Ethernet connectivity to the LOGO! mid-transfer. The transfer dialog reports a timeout error.
• Wrong access password entered. The LOGO! rejects the transfer and the project is not written.

Network Configuration Verification

The LOGO! onboard web server listens on TCP port 80 of the IP address configured in the LOGO! Ethernet settings. Verify the configuration with the following steps:

1. From the LOGO! onboard display, navigate to ESC > Setup > Network. Confirm the IP address, subnet mask, and gateway match the engineering PC subnet.
2. From the engineering PC, open a command prompt and run ping <LOGO_IP_address>. Confirm four replies with sub-10 ms latency on a local Ethernet segment.
3. From the same command prompt, run curl -v http://<LOGO_IP_address>/. Confirm the response code is 200 OK and the body contains the LWE project HTML. A 404 response with HTML body indicates the SD card / deployment problem discussed above. A connection refused indicates an IP, subnet, or firewall problem and is unrelated to LWE.

For a layered diagnostic, capture the HTTP exchange with the following minimal test using curl:

curl -I http://192.168.0.10/
curl -I http://192.168.0.10/user/
curl -I http://192.168.0.10/index.htm
curl -v http://192.168.0.10/ 2>&1 | grep -E "HTTP|Location|Content-Type"

A 200 OK on / but 404 on /user/ indicates the LOGO! is serving only the base web pages; the LWE project was not deployed. A 404 on all three confirms the SD card is unreadable or empty. Use the -v flag to capture full request and response headers including the Server: line, which on a successful response will read Server: LOGO!.

Web Server Authentication

The LOGO! web server implements HTTP Basic authentication on protected paths. The credentials are configured in the LOGO! Soft Comfort program under Tools > Ethernet Connections > Web Server Access. Default values:

The browser authentication prompt appears the first time the protected URL is accessed in a session. The credentials are stored in the browser cache for the duration of the session and must be re-entered after each browser restart.

Firmware Update Procedure

If the LOGO! is confirmed as -0BA0 and LWE support is required, perform a firmware update. Note that LOGO! 8.x firmware revisions are tied to specific hardware revisions; not every -0BA0 base unit can be updated to -0BA1 or later. Some revisions require the unit to be returned to Siemens for a factory upgrade.

1. Identify the exact hardware revision. Power off the LOGO!, remove the SD card, and read the hardware revision code printed next to the order number on the side label (e.g., FS:01, FS:02, FS:03).
2. Check the Siemens Industry Online Support for a firmware update package matching the hardware revision. Use the search term "LOGO! 8 firmware update" and filter by order number suffix.
3. Download the firmware update package (typically a ZIP containing the LWE update tool and a .upd file).
4. Follow the Siemens firmware update procedure: connect the PC to the LOGO! Ethernet port, insert an SD card containing the firmware file, navigate to ESC > Setup > Firmware Update on the LOGO!, and confirm the update.
5. After the update completes, power-cycle the LOGO! and verify the part number displayed in Diagnostic > Hardware > Module now ends in -0BA1 or -0BA2.

Browser and Cache Troubleshooting

Browser caching can mask a successful resolution with a stale 404 response. After the LWE transfer completes, force a hard refresh:

If the 404 persists after a hard refresh, disable browser extensions that intercept HTTP traffic (ad blockers, privacy extensions, corporate proxies) and retry. Use an incognito / private window for a clean test without cached credentials or cookies.

Advanced Troubleshooting Matrix

Use the following matrix to map symptoms to corrective actions. Apply the highest-probability corrective action first.

Network Topology and Request Flow

The following diagram illustrates the request flow from a client browser through the LOGO! onboard web server to the SD card file system for an LWE user web page.

Verification Checklist

After applying the corrective action, verify the following before declaring the issue resolved:

• LOGO! part number confirmed as -0BA1 or -0BA2.
• microSD card reported present and readable under Diagnostic > Hardware > SD Card.
• LWE project builds with zero errors and zero warnings.
• LOGO! was in STOP mode during the LWE transfer; transfer reports success.
• Browser navigation to http://<LOGO_IP>/ returns 200 OK on index.htm.
• All CSS, JavaScript, and image sub-resources return 200 OK (verified via browser Network tab).
• Live LOGO! tag values update in the browser visualization when triggered from LOGO! Soft Comfort online mode.
• Web server survives a LOGO! power cycle without reverting to 404.
• Hard refresh (Ctrl+Shift+R) does not reintroduce the 404.

Frequently Asked Questions