How to fix the error: "Library dbcapi.dll cannot be loaded"

Background: 
 
TWS users may receive the following error message upon configuring TWS to use the eSignal data feed:
 
 
This error may appear for the following reasons:
 
Issue A - You are not using the 32 bit version of TWS and/or eSignal:
The 32-bit versions of both TWS and eSignal have to be installed for the integration to work. In the section below you will find the instructions for installing the 32-bit TWS. Should you need assistance with the installation of the 32-bit eSignal, we suggest you to contact the eSignal customer support.
 
Issue B - There is an incompatibility with the file C:\Jts\dbcapi.dll:
To use 32-bit eSignal version 12, an incompatibility with the C:\Jts\dbcapi.dll file must be fixed. This involves copying a file from the eSignal installation and renaming it to dbcapi.dll. 
 
Note: On certain systems you will need to apply the fixes for both issue A and B. If you applied the fix for issue A (or if you are already sure you are using the 32 bit version of both platforms) and you are still receiving the error message, then please apply as well the fix for issue B.
 
 
 
Instructions to resolve issue A
Installing 32-bit TWS
 
Please open the page http://www.ibkr.com in your browser and perform the steps below:

1) Click on the LOG IN button at the top right corner of the page.

2) Under the section TRADER WORKSTATION, click on TWS Latest.

3) On the next page, click on the link Download for Other Operating Systems.
 

4) Click on the item Windows 32-bit.

5) Make sure that the description under the DOWNLOAD button has changed to "Windows: 32 bit". Click now on DOWNLOAD.

6) Launch the downloaded file. The Trader Workstation installation will start. At this point you may see the warning message "Trader Workstation latest is already installed...". Ignore this warning and click on the button Next > to continue the installation.

 

7) Your "Trader Workstation" Desktop icon will be automatically updated. You can now launch the 32-bit Trader Workstation by a double click on that icon.

If you have launched the 32-bit TWS and the 32 bit version of eSignal but you still receive the same error message, please follow as well the instructions below

 
 
Instructions to resolve issue B
Replacing dbcapi.dll for compatibility between 32-bit TWS and 32-bit eSignal 12

To correct an incompatibility with the dbcapi.dll file, we will replace that file with another version of it taken from the eSignal installation folder. Please follow the steps below to perform the substitution:  

1) Navigate to C:\Jts and rename the file dbcapi.dll to dbcapi_old.dll

2) Navigate to the directory where 32-bit eSignal 12 is installed (most commonly C:\Program Files (x86)\Common Files\Interactive Data\DM)

3) Copy dbcapi_vc8.dll from that directory into the C:\Jts directory.

4) Move to the C:\Jts directory

5) Right click on the dbcapi_vc8.dll file (now in the C:\Jts directory) and select rename. Type dbcapi.dll as the new filename.

6) TWS is now ready to accept the eSignal data feed.