This section includes important and useful comments by users.

Added Mar 24, 2010

I just reviewed Web resources on this problem. I suggest that before you proceed with my solution, please check out Adobe's posting at It was not available at the time I posted this solution. It does not mention Windows Vista or Windows 7, but their Windows XP solution should work equally well for these newer operating systems. This Adobe solution is similar to mine. I do have confidence in my solution, however, as do others, judging from the following recent comment.

Joseph wrote on Mar 14, 2010:

"Just applied your remedy to the Adobe 9.3 Installation error(s) - of course YOU know - it worked perfectly!!! Thank you. Had the 1404 & several 1406."

As noted on the Jan 17, 2008 entry below, for the seven months after posting this solution in Jun 2007, I received about 32 hits per day. The hit rate has diminished but it is not moving asymptotically to zero, as one might hope. Here is a graph of the hit rate over the past year. Note the spike around Christmas-time.

Hits/Day on this Page for 12 Months Ending Mar 23, 2010

Added Aug 12, 2008

Here is another potential solution to the Error 1406 problem, supplied by Bob on Jul 5, 2008:

"I have stumbled on another solution which may be easier. I was starting to try your solution after my CS3 install of Acrobat 8 failed, but I needed a standalone install file for Acrobat 8. But I only found a trial for Acrobat 9 on the Adobe web site. So I loaded that instead and DID NOT get the error messages; Adobe may have fixed the problem in version 9. So I then just uninstalled the version 9 trial and tried my CS3 install of Acrobat 8 and it worked!"

Deconstructing Bob's solution, you might attempt the following:

  • Go to the page on Adobe's Web site that enables you to download a free 30-day trial version of Adobe Acrobat 9 Pro:
  • Click on the Create an Adobe account button and create an account. To do so is a pain—but consider what you stand to gain. I had created an Adobe account several years ago; when I logged on under that account today, Adobe sent me a link to the trial version via email. When you receive the email, click on the link and download and install the trial version.
  • After installation, which hopefully will proceed without a hitch, uninstall it by going to start -> Control Panel -> Add or Remove Programs (Windows XP) or start -> Control Panel -> Programs and Features (Windows Vista).
  • If Bob's solution works, then the Error 1406 cause will have been fixed. Now you should be able to immediately reinstall your Adobe Acrobat 8 without difficulty.

Note that this is an unverified solution, but if it works, it is a simpler method for clearing the Error 1406 than my solution below. If it fails, follow the recipe below in the section entitled The Problem Description to clear the error.

Added Mar 29, 2008

I am sharing the following comments from Kathy since they may be useful to someone. However, I don't have an adequate understanding of the registry to expand on this information:

I'm running on Windows XP Home Edition. When I attempted to change permissions for the various keys from Read to Full Control, though my access level was Administrator, it failed with a message of access is denied.

After hunting down some discussions on changing permissions, I discovered that I was denied access because I was not the owner of these keys. For reasons I don't fully understand, the owner [ed: see Owner tab in screenshots below] was something that looked to be a key listed under Google Desktop. My machine did ship with a stripped-down version of Acrobat, so maybe that's where it originated.

Anyway, once I changed the owner of each key and each subkey (since ownership changes cannot be propagated down the tree), I was able to change the permissions just as you described.

Added Mar 14, 2008

A couple days ago Regina informed me that she had been unsuccessful in installing Acrobat 8:

I have just about wasted 2 days - 4 calls to Adobe support and still have not installed 8.

She stated she had been unable to locate the registry folder ("I do not have that registry folder in my registry") identified in the first screen shot below.

I suggested she look again. Today she wrote back:

Yesterday morning, w/ a fresh mind, I did find the folder and started resetting permissions. I had to do it about 5 times. Also, I was on the phone w. adobe support while I was doing it and they tried to help me but it did not work until I told them about your solutions page. Together we found the folder and the support person told me that he will add your web link to his support material because that’s really what made the install possible.

Thanks for helping to spread the word, Regina. (Although I'm flattered to learn that an Adobe support person has added this page to his support material, Adobe and its customers would be better served if Adobe created an update to fix the error 1406 or prevent it from occurring in the first place.)

Added Jan 17, 2008

I have had a phenomenal amount of feedback from this solution which I posted on Jun 27, 2007. (As of this date, this page has received over 6,500 hits.) Comments have been uniformly positive. I am grateful that my posting has been so beneficial. Recently, on Jan 17, 2008, Aaron shared the following observation with me:

Just wanted to add that an additional step that may be required is to log in as the local "Administrator" account in order to make the permissions changes to the registry keys you mentioned.

For some reason, even though I was logged in on an administrator type account, the registry would not allow me to change the permissions on those keys you mentioned (Full Control, Inherited Permissions, Replace Child...) until I logged out of that account and logged back in as THE local "Administrator" account.

I found out that little bit of information from the Adobe forums (link was provided from your article as well).

On my PC I am the sole user. When I select User Accounts in the Control Panel I see the following:

User Accounts on my PC

Having only a single Administrator account, I never would have observed this issue, as his advice applies only to someone who has more than one Administrator account. Thanks, Aaron.

The Problem Description

This section defines the problem and specifies a solution that has received positive reviews.

My goal was to install two recently-purchased software packages:

  • Adobe Acrobat 8 Professional

  • Adobe Creative Suite 3 Web Premium

Previously, I had removed Adobe Acrobat 7. I also have Adobe CS2 on my PC, but I didn't plan to remove it until after I was satisfied with CS3.

I started installing Adobe Acrobat 8. Within minutes I received the following error message:

Error 1406. Could not write value ThreadingModel to key \Software\Classes\CLSID\{06849E9F-C8D7-4D59-B89D-784B7D6BE0B3}\InprocServer32.

Verify that you have sufficient access to that key, or contact support personnel.

I couldn't complete the installation. If I clicked Ignore and continued, I received about 15 more similar errors before installation finished. Because of these errors, the program didn't work.

The error 1406 failure is addressed in Adobe user to user forums at [search for "error 1406"], and solutions are suggested, but the bottom line is this. For this program (and presumably CS3 Web Premium because it includes Acrobat) to install, either you must alter the registry—a risky process—or you need a fix from Adobe. I ran the Adobe-provided program referenced in the forum, Fix_1406ACL.exe; it did not fix my problem, and others said it did not work for them.

Since Adobe could not provide a solution I needed to correct errors in the registry. The registry correcting solutions mentioned in the forum were either vague, poorly written (and this applies to Adobe's Knowledge Base entry at, simply wrong, or didn't apply to my specific Error 1406 problem. (Addendum dated Mar 24, 2010: This KB entry has been updated and now mimics my solution, but may be more elegant--try it first!!)

The forum mentions MSI log files. During my installation attempt, the file C:\Documents and Settings\<username>\Local Settings\Temp\MSI6d2e6.LOG was created. It contained only the following:

Error 1406.Could not write value ThreadingModel to key \Software\Classes\CLSID\{06849E9F-C8D7-4D59-B87D-784B7D6BE0B3}\InprocServer32. System error . Verify that you have sufficient access to that key, or contact your support personnel.

=== Logging stopped: 6/20/2007 18:20:24 ===

Problem Analysis

To start the Registry Editor, click start —> run, type regedit, and click OK. Navigate to the key referenced above: My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\
. You should see the following Registry Editor screen:

Registry InprocServer32 key

Right-click on InprocServer32 (highlighted above), click Permissions… You’ll see:

Permissions for InprocServer32

Click Advanced. You’ll see:

InprocServer32 Permission List

The cause of Error 1406 is the InprocServer32 key has Read permission only and therefore cannot be altered. (I determined later that the installation program is attempting to change the default value to:
C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelper.dll).

Problem Solution

Note that in the Advanced Security Settings for InprocServer32 dialog box above, under "Permission entries:" Permission is Read and this is Inherited From "MACHINE\SOFTWARE\ Classes\CLSID\{06849E9F-C8D7-4D59-B89D-784B7D6BE0B3}" (the last part of the name is not shown in the screen shot above). When you look at that parent key (go ahead and select it in the left panel of the Registry Editor, right click, click Permissions…, and click Advanced) you’ll see that Permission is Read and it is <not inherited>. Therefore, if you change the permission of that key to Full Control and allow child objects to inherit it, the problem with this key will be solved. Note that there are five child objects, not just InprocServer32, but ProcID, Programmable, TypeLib, and VersionIndependentProgID. Since all four of these other child objects have permission attributes identical to that of InprocServer32, giving them the Full Control permission attribute should cause no problem and in fact is probably necessary.

Thus, in summary, the solution is to change this key's permission from Read to Full Control, rerun the Acrobat installation, and as each additional 1406 error appears, correct it and click Retry. That's it. Details follow.

Applying the Solution

Part 1: Fix InprocServer32 Permission

While still in the Registry Editor, select the parent key My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\
. Right click, click Permissions…, and the following dialog box will appear:

InprocServer Permissions before Changed to Full Control

Next to Full Control, check Allow. Click Apply. Click Advanced and the following dialog box will appear (note that because Apply was clicked, the Full Control permission attribute is shown) :

InprocServer Permission List after Permission Changed to Full Control

To force this change to propagate to child objects, check the box Replace permission entries on all child objects with entries shown here that apply to child objects. Click OK. The following warning will appear:

Confirmation Message Detailing Change that Was Made

Click Yes. Click OK in the Permissions dialog box. Leave the Registry Editor open as you'll be making additional changes below.

To verify that these changes have propagated to child objects, examine the permission of InprocServer32. You’ll see that Full Control is now checked in the Permissions dialog box and that Full Control is now the permission shown in the Advanced Security Settings dialog box.

Part 2: Reinstall Adobe Acrobat 8

After correcting the InprocServer32 key's permissions, I reinstalled Adobe Acrobat 8 Professional. My notes from this installation appear below.

I closed all programs, turned off anti-virus software, and began installation, expecting error messages. Three minutes into the installation, I received the following error message:

Error 1406.Could not write value to key

\Software\Classes\AcroIEHelper.AcroIEHlprObj\CLSID. Verify that you have sufficient access to that key, or contact your support personnel.

I opened the Registry Editor and navigated to My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AcroIEHelper.AcroIEHlprObj\CLSID. Its permissions were READ, inherited from its parent. As described earlier, I navigated to the parent (...\Classes\AcroIEHelper.AcroIEHlprObj), changed its permission from READ to FULL CONTROL, and directed that the child objects inherit this permission.

I returned to the installation program and clicked Retry.

The next error message was:

Error 1406.Could not write value to key

\Software\Classes\AcroIEHelper.AcroIEHlprObj.1. Verify that you have sufficient access to that key, or contact your support personnel.

I navigated to My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AcroIEHelper.AcroIEHlprObj.1, changed its permission from READ to FULL CONTROL, and directed that the child objects inherit this permission.

I returned to the installation program and clicked Retry.

The next (and last) error message was:

Error 1406.Could not write value to key

\Software\Classes\TypeLib\{5F226421-415D-408D-9A09-0DCD94E254B8}\1.0\FLAGS. Verify that you have sufficient access to that key, or contact your support personnel.

I navigated to My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\
, changed its permission from READ to FULL CONTROL, and directed that the child objects inherit this permission.

I returned to the installation program and clicked Retry.

The installation completed.


Because my son works for Adobe, I was able to purchase this software at a discount. I carelessly had purchased both Acrobat 8 and CS3 Web Edition, which contains Acrobat 8. When I realized this, I decided to use the Acrobat installation as a means of eliminating these 1406 errors. Once they were eliminated, I uninstalled Acrobat (without registering it). Then I installed CS3 Web Edition, which went smoothly and error-free.

Hope this helps.