When deploying all the Microsoft Dynamics AX 2009 SSRS Reports using the "Microsoft Dynamics AX 2009 Report Deployment" application you may hit the following error after a while:
 
Client found response type of 'text/html;charset=utf8;' but expected 'text/html'
One of the reasons we find that the error commonly occurs due to the length of time it takes to deploy the reports and the following 4 suggestions may help in reducing the deployment time and load, try each one in the order given:
 
(1) Reduce the number of Reports Libraries and Reports per Language. By default, reports from all languages that are enabled in the LANGUAGETABLE of the AX database are deployed (this can be over 40+ languages). Prior to the reports deployment you can change the LANGUAGETABLE so that it only deploys Reports for the languages (cultures) that you want deployed.
To do this set the value 0 in the LabelFile column of the LANGUAGETABLE table for languages (LANGUAGEID column) you dont want to deploy reports for.
IMPORTANT NOTE: Make a backup of the table and/or database before changing the values. Also be aware that if you have any AX clients that has references to those languages that are disabled then they won't be able to log into AX.
Here is a sample SQL update statement to set the value zero in the LabelFile column for all languages except the ones specified in the WHERE clause:
 
e.g. The following statement will NOT update the values for LANGUAGEID en-us or sv-fi, but set the Value 0 for all other LANGUAGEID values
UPDATE LANGUAGETABLE SET LabelFile=0 where LANGUAGEID <> 'en-us' and LANGUAGEID <> 'sv-fi'

 
(2) If you are using Windows Server 2008/R2 then run the AX 2009 Reports Deployment tool using elevated priviledges (secondary mouse-click on the Reports Deployment Tool and select "Run as Administrator" ) and/or temporarily disable Windows Server 2008 User Account Control (disabling UAC requires a reboot of the system), until the reports are deployed.
 
(3) Deploy a few libraries at a time rather than all of them in one go

(4) If you have Anti-Virus software/services installed than temporarily put an exclusion rule for the AX 2009 Reports Deployment tool (AxReports.exe) and visual studio isolated shell (devenv.exe) and exclude the user temporary folder from being scanned and/or Temporarily stop/disable Anti-Virus software and services during the deployment only.