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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(156.8, 49%, 25%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESL%3C/text%3E%3C/svg%3E)
In SharePoint 2019, after applying KB 5002639 and subsequent updates, deploying BCS solutions is not possible.
Error messages is
DotNetAssembly/WebService system type is not supported.
Error was encountered at or just before Line: '4' and Position: '6'.
Error log: BCS_Deploy_Error.txt
---The problem has been resolved----
Thankyou @Marco Siciliano !!
A family of Microsoft on-premises document management and storage systems.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(160, 17%, 25%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EYJ%3C/text%3E%3C/svg%3E)
Do you mean you have installed the latest updates KB 5002657and KB 5002664?
Yes, my sharepoint farm installed KB 5002657and KB 5002664 . However, the same error occurs.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(38.4, 53%, 13%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMF%3C/text%3E%3C/svg%3E)
@seungjae lee here is the catch, it appears that MS Team has added a deprecation in the BDC Service (This is extracted from Decompiled Microsoft.SharePoint.dll
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(9.6, 47%, 10%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ETS%3C/text%3E%3C/svg%3E)
Good News,
Microsoft released two updates on August 12th: KB5002771 and KB5002772.
As reported on the official page, these updates resolve the issue in question.
On the official update page there is a detail in the section: improvements and solutions.
Answer accepted by question author
@seungjae lee here is the catch, it appears that MS Team has added a deprecation in the BDC Service (This is extracted from Decompiled Microsoft.SharePoint.dll)
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(236.8, 90%, 32%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMK%3C/text%3E%3C/svg%3E)
We are also running into the same issue for several BDC models that we maintain. I don't see any mention of the BCS being deprecated for SharePoint 2016/2019, although it was deprecated in SharePoint Online in September (which is when this patch was released). Is this an issue that they introduced by mistake when deprecating it for SharePoint Online?
It has to be escalated to Microsoft to see what's happening.
How do we escalate the issue to Microsoft?
Hi @Michael Koger, Please refer to this: Global customer service phone numbers.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(112.00000000000001, 82%, 20%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESR%3C/text%3E%3C/svg%3E)
Hello everyone
This accepted answer is not a solution.
Please check this announcement:
https://learn.microsoft.com/en-us/sharepoint/business-connectivity-services-retirement
It should not impact SharePoint 2016 & 2019 Server (on on-premises).
This feature will remain supported in SharePoint Server 2016 and SharePoint Server 2019 until those products reach their end of support date of July 14, 2026.
Is there anyone who can comment on this?
It is really a problem for us!
Thanks,
Roger
Effectively, its not a solution, and its a reality, i decompiled the Microsoft.SharePoint.dll to discover this, and its not mentioned in any KB of microsoft as i know, and i will add you something new, we applied a more recent update and the DotNetAssembly BCS Types does not work on deployment and also on Loading (MS added the Loading one recently) so they are retiring it even on prem.
What you can do? you can use the other systemtypes to construct you bcs model :
Has anyone used one of the two scripts and solved the problem:
-----
Scripts1
----
Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue
# Re-enable support for DotNetAssembly and WebService type BDC applications
$farm = Get-SPFarm
$farm.ServerDebugFlags.Add(57007) # Trust type DotNetAssembly
$farm.ServerDebugFlags.Add(57008) # Trust type WebService
$farm.Update()
iisreset
--------
Script2
------
add-pssnapin *
$f = Get-SPFarm
$types | ForEach-Object {
$f.AddGenericAllowedListValue("SPSerializationCustomizedAllowList", "???")
}
$f.Update()
iisreset
This second script is missing parameter
Thamks
@Marco Siciliano Thank you. The problem has been resolved. Bless you.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(179.20000000000002, 42%, 27%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAB%3C/text%3E%3C/svg%3E)
What parameter should I insert instead of "???" ? Or should I execute it as written?
I just typed $f.AddGenericAllowedListValue("SPSerializationCustomizedAllowList", "???") exactly
These scripts did not solve the problem for SP2016
@seungjae lee can i confirm the sharepoint version and the second parameter used? thanks
@Marco Siciliano I use SharePoint 2019 with lastest patch(KB5002754, KB5002753. https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/). And i just used it as written ???.
This script does nothing, besides restarting IIS: ;-)
--------
Script2
------
add-pssnapin *
$f = Get-SPFarm
$types | ForEach-Object {
$f.AddGenericAllowedListValue("SPSerializationCustomizedAllowList", "???")
}
$f.Update()
iisreset
But the Script1 helped, at least partly. Webparts using BCS started to work again, but there is still the issue that the items in list views cannot be returned. Script2 might help in this regard, however, you really need to know the type.
Update: Trying again viewing the list items (in the list views) - all fine now. Great!
The problem SP2016 was solved by installing the KB5002771 and KB5002772 patches on August 12, 2025.
Hi everyone,
just patched our SharePoint 2016 farm to 16.0.5513.1001 with the July 21 2025 security updates:
Now all External Lists that use a DotNetAssembly BDC model blow up.
ULS spits out:
"
System.InvalidOperationException:
DotNetAssembly/WebService system type is not supported.
Error at Line 4, Position 6
"
Database/OData ECTs are fine — only the .NET ones die.
Based on what I’ve read in this thread and on my own experience, I have to conclude that this patch has re‑introduced the same issue we saw with the previous one.
Yes, they introduced the DotNetAssembly/WebService SystemTypes Retirment
here is the catch, it appears that MS Team has added a deprecation in the BDC Service (This is extracted from Decompiled Microsoft.SharePoint.dll)
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(284.8, 34%, 37%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAF%3C/text%3E%3C/svg%3E)
Hello everyone
Maybe related/same issue here after applying patch KB5002754 and KB5002753 (SharePoint 2019 on-premises):
Error while crawling LOB contents. ( Error caused by exception:
System.InvalidOperationException The Model contains LobSystem (External
System) of Type 'DotNetAssembly' which is not supported.; SearchID =
...-...-...-...-... )
A.
here is the catch, it appears that MS Team has added a deprecation in the BDC Service (This is extracted from Decompiled Microsoft.SharePoint.dll)
Hello everyone
The Accepted answer is not a solution.
Please check this announcement:
https://learn.microsoft.com/en-us/sharepoint/business-connectivity-services-retirement
It should not impact SharePoint 2016 & 2019 Server (on on-premises).
This feature will remain supported in SharePoint Server 2016 and SharePoint Server 2019 until those products reach their end of support date of July 14, 2026.
Is there anyone who can comment on this?
It is really a problem for us!
Thanks,
Roger
Hi @seungjae lee ,
Welcome to Q&A forum!
I have done a lot of research, but there is not much reference material for your situation. Based on the information you provided, it can be determined that it is caused by an update, but the recent updates do not specify the impact on BCS. You can check if there are any Windows updates that have not been installed, which sometimes has an impact. If it doesn't work, you can try to roll back the update or wait for the next update to see if it can solve the problem. However, the forum engineer has limited authority. If you need to roll back the update, you need to escalate the issue. You need to contact Microsoft directly to operate. The support team over there has the correct escalation channels, and they can devote more resources and investigate the behavior from the backend as quickly as possible. They can also remotely check the behavior on your side. They can even help you find the root cause of the issue. For reference: Global customer service phone numbers. This is the most efficient way to handle this thread given the circumstances. I'm confident that our expert engineers over there can resolve this issue efficiently and accurately.
Good day! Happy New Year to you in advance!
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I understand there is no dedicated personnel for testing SharePoint 2019 BCS. This is disappointing.
This is a simple test.
Install SharePoint 2019 and applying patches, and then create and deploy a BDC Solution in Visual Studio.
BDC Solution deployed but I cannot find deployed BDC.
So I manually upload the bdcm file, a 'DotNetAssembly/WebService system type is not supported.' error occurs.
Hi @seungjae lee ,
Sorry to hear that you're having this problem, but the forum can only do so much for this issue. I still recommend that you contact Microsoft directly for a better solution.
If the answer is helpful, please click "Accept Answer" and kindly upvote it.