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Help! Applying a patch broke my dev instance.

  • September 18, 2026
  • 14 replies
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MichaelShirk
Captain II
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Using patch tool version 1.18.1.0. I attempted to update my developer instance

from  26.100.0175 to 26.100.0175.5  

I don’t recall seeing an error in the terminal, but I also don’t recall closing the terminal. 

I went to load the site and got the following server error. “ The type or namespace name 'Maintenance' does not exist in the namespace 'PX.Data' (are you missing an assembly reference?)” 
 

 

After some digging I discovered that PX.Data.dll was missing from my instance bin folder. 

The patch tool errors now if I try to run any of the commands. 

 

Attempting to run the wizard to upgrade/repair the site also errors on PX.Data.dll. 

 

Anyone else seen anything like this?

Best answer by andreybudaev87

Hi ​@MichaelShirk ,

That event log is exactly what we needed.

 

Confirmed: two of the runs crashed on a PatchTool bug

At 13:43:22 and 13:45:09 PatchTool terminated with an unhandled exception:

System.UnauthorizedAccessException   at System.IO.File.InternalDelete(...)   at PatchTool.Services.CacheService.FetchPatchArchive(...)

It was trying to delete a stale cached patch archive at C:\ProgramData\AcumaticaPatchTool\26.100.0175-2.zip and got "access denied". That delete isn't error-handled, and the exception isn't caught anywhere, so the process dies instantly with nothing written to the log - which is why your PowerShell window just vanished with no message. This is a defect on our side and we'll fix it.

The third run is a separate problem

The run at 13:45:40 got much further — it downloaded, backed up and patched all files, then the log stops while starting npm ci. For that one there is no Application Error, no WER report and no .NET Runtime event at all in the 13:40–13:50 window, so it did not crash. It was either killed or left hanging.

Two things would help here:

  1. The Defender output — you sent the Application/System query but not the two Defender ones. Please run those as well, and let us know if any third-party security/EDR product is installed (Defender's own log will look clean if a different product is responsible).
  2. Get-ChildItem "C:\Acumatica\AcumaticaSites\Shedworks26R1\Shedworks26R1\App_Data\Logs\npm-2026-09-18-13-46-20*" — if only the -arguments.txt file is there, npm never finished.
Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.

14 replies

JKurtz29
Varsity III
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  • JKurtz29
  • Varsity III
  • September 18, 2026

I haven’t seen that.  Have you tried going into the ERP Configuration Wizard and use the Perform Application Wizard and selecting the option to upgrade the website?  That should write the files back out to the website.

Once you get back in, you can try patching again, and republishing your customizations.

Jerry Kurtz | Senior Director Application Development | JKurtz@algorithminc.com
    MichaelShirk
    Captain II
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    • MichaelShirk
    • Author
    • Captain II
    • September 18, 2026

    ​@JKurtz29 Perhaps you were typing your response when I updated the post to add that I’ve already tried that!😅

    Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
    JKurtz29
    Varsity III
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    • JKurtz29
    • Varsity III
    • September 18, 2026

    ​@JKurtz29 Perhaps you were typing your response when I updated the post to add that I’ve already tried that!😅

    Or I was just lazy and didn’t read it all :/

    I imagine you’ve also tried doing an IISRESET from and administrator command prompt or rebooted your machine to recycle IIS in case it somehow has a file handle in memory or some other strange thing going on?

    Have you also tried adding a new instance in a different folder, but pointing to your existing database to see if that works?

    Jerry Kurtz | Senior Director Application Development | JKurtz@algorithminc.com
      andreybudaev87
      Acumatica Moderator
      • andreybudaev87
      • Acumatica Moderator
      • September 18, 2026

      Hi ​@MichaelShirk 

       

      After PatchTool performs any operation, a log file is written to the disk. Please attach it. 

        darylbowman
        Captain II
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        Did you try just pasting in PX.Data.dll from a different 26 R1?

        Daryl ⚡Freelance developer 🛒Check out my products 👉🏻deftstrokesdev.com/index.php/products ⏩linkedin.com/in/darylbowman
          MichaelShirk
          Captain II
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          • MichaelShirk
          • Author
          • Captain II
          • September 18, 2026

          ​@JKurtz29  Those are the things I’m in the process of trying. 

          Thanks! 

          ​@andreybudaev87 Where do those get stored?

          Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
          andreybudaev87
          Acumatica Moderator
          • andreybudaev87
          • Acumatica Moderator
          • September 18, 2026

          ​@MichaelShirk 

           

          In the folder with patchtool.exe

            MichaelShirk
            Captain II
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            • MichaelShirk
            • Author
            • Captain II
            • September 18, 2026

            ​@darylbowman I tried that, but even with admin permissions I was still blocked. 
            Claude and ​@JKurtz29 seem to be right, because after a reboot I could rebuild the site and it loads again. 

            “

            When a file is deleted while a process still holds an open handle to it, Windows puts it in a delete-pending state: the name disappears from directory listings, but the entry stays reserved in the directory until the last handle closes. Any attempt to create a new file with that name returns ERROR_ACCESS_DENIED, which .NET surfaces as UnauthorizedAccessException. That matches everything you've seen — invisible file, writable folder, clean ACL, test.txt succeeds, PX.Data.dll doesn't.

            Reboot the server, then retry the copy. That releases the handle unconditionally and is faster than hunting it down.

            ” 

            I’ll reattempt the patch now.

            Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
            MichaelShirk
            Captain II
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            • MichaelShirk
            • Author
            • Captain II
            • September 18, 2026

            ​@andreybudaev87 the second attempt did exactly the same thing. 
            I’ve attached the log file. 

            I ran the patchtool. The process looked like it was running successfully, then suddenly powershell closed. 

            I try to open the site and it’s broken again with the same message. 
            I checked and PX.Data.dll is also missing from the instance bin folder again. 

             

            Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
            andreybudaev87
            Acumatica Moderator
            • andreybudaev87
            • Acumatica Moderator
            • September 19, 2026

            Hi ​@MichaelShirk 

            Thanks for the log. Short version: PatchTool isn't deleting PX.Data.dll, and it isn't crashing on its own. Something outside is killing the process and removing the file — most likely an antivirus / EDR product on that machine.

            The patch itself ran fine: everything was downloaded, verified, backed up, and all files were written, including PX.Data.dll. The log then just stops mid-step, with no error and no rollback. That's a hard kill, not a failure.

            Two things point away from the patch tool itself:

            • Your PowerShell window closed by itself. If the tool had crashed, PowerShell would have stayed open with an error. A whole console window disappearing means the process tree was killed externally.
            • PX.Data.dll was written successfully and then vanished. The tool has no code path that deletes files from Bin — that looks like a quarantine.

            It also reproduces at exactly the same point every time, which suggests a deterministic detection rule.

             

            Could you run these and send the output?

            Get-MpThreatDetection | Where-Object {$_.InitialDetectionTime -gt (Get-Date).AddDays(-3)} | Format-List InitialDetectionTime,ThreatID,Resources,ActionSuccess
            Get-WinEvent -LogName "Microsoft-Windows-Windows Defender/Operational" -MaxEvents 100 | Where-Object Id -in 1006,1007,1015,1116,1117 | Format-List TimeCreated,Id,Message
            Get-WinEvent -FilterHashtable @{LogName='Application','System';StartTime=(Get-Date '2026-09-18 13:40');EndTime=(Get-Date '2026-09-18 13:50')} | Format-List TimeCreated,Id,ProviderName,Message

            If you're running third-party security software in addition to Defender, the commands above will come back clean even if that product is the culprit — so please also let us know what else is installed on the box.

             

            If it's confirmed, add exclusions for:

            • C:\Acumatica\AcumaticaSites\Shedworks26R1\ (whole tree)
            • C:\ProgramData\AcumaticaPatchTool\
            • C:\Program Files\AcumaticaTools\NodeJS\
            • the PatchTool.exe, node.exe and npm.cmd processes
              MichaelShirk
              Captain II
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              • MichaelShirk
              • Author
              • Captain II
              • September 21, 2026

              ​@andreybudaev87 I’ve attached the output from your diagnostic scripts. 

               

              Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
              andreybudaev87
              Acumatica Moderator
              • andreybudaev87
              • Acumatica Moderator
              • Answer
              • September 21, 2026

              Hi ​@MichaelShirk ,

              That event log is exactly what we needed.

               

              Confirmed: two of the runs crashed on a PatchTool bug

              At 13:43:22 and 13:45:09 PatchTool terminated with an unhandled exception:

              System.UnauthorizedAccessException   at System.IO.File.InternalDelete(...)   at PatchTool.Services.CacheService.FetchPatchArchive(...)

              It was trying to delete a stale cached patch archive at C:\ProgramData\AcumaticaPatchTool\26.100.0175-2.zip and got "access denied". That delete isn't error-handled, and the exception isn't caught anywhere, so the process dies instantly with nothing written to the log - which is why your PowerShell window just vanished with no message. This is a defect on our side and we'll fix it.

              The third run is a separate problem

              The run at 13:45:40 got much further — it downloaded, backed up and patched all files, then the log stops while starting npm ci. For that one there is no Application Error, no WER report and no .NET Runtime event at all in the 13:40–13:50 window, so it did not crash. It was either killed or left hanging.

              Two things would help here:

              1. The Defender output — you sent the Application/System query but not the two Defender ones. Please run those as well, and let us know if any third-party security/EDR product is installed (Defender's own log will look clean if a different product is responsible).
              2. Get-ChildItem "C:\Acumatica\AcumaticaSites\Shedworks26R1\Shedworks26R1\App_Data\Logs\npm-2026-09-18-13-46-20*" — if only the -arguments.txt file is there, npm never finished.
                MichaelShirk
                Captain II
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                • MichaelShirk
                • Author
                • Captain II
                • September 22, 2026

                ​@andreybudaev87 thanks again for your time! 


                I did have BitDefender on my machine, so I’ll assume that was what was crashing it. 
                I have successfully applied patches to my dev instance previously, so I’m wondering if it was flagged this time because I was running it directly from my downloads folder. 

                 

                I’ll wait to test this theory until October 1st when Patch 6 is available.

                Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
                  MichaelShirk
                  Captain II
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                  • MichaelShirk
                  • Author
                  • Captain II
                  • September 25, 2026

                  Yep, it was Bitdefender.  

                  Haha. Found my dlls!

                   

                  Michael Shirk, Pine View Buildings, LLC - If a member helped you, please *Like* their post. If a member provided an answer to your question, please mark it as *Best Answer*.
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