The error shown in the screenshot includes the code ERROR_VUE_WIDE_BLOCK. This typically means the Pearson VUE account used for exam payments and scheduling has been blocked, usually because of multiple failed payment attempts.
To resolve this and be able to pay and book the GH-300 exam slot again, contact Pearson VUE support through the Microsoft Certification support channel and ask them to remove the ERROR_VUE_WIDE_BLOCK on the account. Use the Pearson VUE/contact link provided on the Microsoft Certification support page at:
After Pearson VUE removes the block, return to the exam registration page and try scheduling and paying again.
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